This bug is still present in Ubuntu 17.10 Artful. I have experienced it after waking up from suspend on a Dell XPS 9360 with a clean Ubuntu install.

Here is the dump:

Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.661562] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.694143] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.726760] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.759262] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.791956] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.824470] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.857075] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.889653] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.922200] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30476.954870] ath10k_pci 0000:3a:00.0: failed to wake target for read32 at 0x0003a028: -110
Dec 26 17:52:04 sabina-XPS-13 kernel: [30477.569491] ath10k_pci 0000:3a:00.0: failed to read device register, device is gone
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669015] ath10k_pci 0000:3a:00.0: firmware crashed! (uuid 283c1469-65cc-447c-a08d-c723b4f1387a)
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669020] ath10k_pci 0000:3a:00.0: qca6174 hw3.2 target 0x05030000 chip_id 0x00340aff sub 1a56:1535
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669021] ath10k_pci 0000:3a:00.0: kconfig debug 0 debugfs 1 tracing 1 dfs 0 testmode 0
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669389] ath10k_pci 0000:3a:00.0: firmware ver WLAN.RM.4.4-00022-QCARMSWPZ-2 api 6 features wowlan,ignore-otp crc32 4d458559
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669634] ath10k_pci 0000:3a:00.0: board_file api 2 bmi_id N/A crc32 07ee144e
Dec 26 17:52:05 sabina-XPS-13 kernel: [30477.669635] ath10k_pci 0000:3a:00.0: htt-ver 3.32 wmi-op 4 htt-op 3 cal otp max-sta 32 raw 0 hwcrypto 1
Dec 26 17:52:05 sabina-XPS-13 kernel: [30478.172084] ath10k_pci 0000:3a:00.0: failed to read firmware dump area: -16
Dec 26 17:52:05 sabina-XPS-13 kernel: [30478.172087] ath10k_pci 0000:3a:00.0: Copy Engine register dump:
Dec 26 17:52:05 sabina-XPS-13 kernel: [30478.302279] ath10k_pci 0000:3a:00.0: [00]: 0x00034400 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:05 sabina-XPS-13 kernel: [30478.434224] ath10k_pci 0000:3a:00.0: [01]: 0x00034800 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:05 sabina-XPS-13 kernel: [30478.565730] ath10k_pci 0000:3a:00.0: [02]: 0x00034c00 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30478.695977] ath10k_pci 0000:3a:00.0: [03]: 0x00035000 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30478.826324] ath10k_pci 0000:3a:00.0: [04]: 0x00035400 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30478.956700] ath10k_pci 0000:3a:00.0: [05]: 0x00035800 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30479.086854] ath10k_pci 0000:3a:00.0: [06]: 0x00035c00 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30479.217234] ath10k_pci 0000:3a:00.0: [07]: 0x00036000 4294967295 4294967295 4294967295 4294967295
Dec 26 17:52:06 sabina-XPS-13 kernel: [30479.217242] ath10k_pci 0000:3a:00.0: failed to reset chip: -5
Dec 26 17:52:06 sabina-XPS-13 kernel: [30479.217244] ath10k_pci 0000:3a:00.0: Could not init hif: -5

The workaround is to manually update to the linux-firmware package in bionic (1.170)

Dell have written an article about it:

http://www.dell.com/support/article/bg/en/bgbsdt1/sln306440/killer-n1535-wireless-firmware-manual-update-guide-for-ubuntu-systems?lang=en

I have been running the package and so far so good.