Test case {index}_dim_brightness_PCI_{Vendor}_after_suspend run failed

[Alex Wen]

Test machine: Tata2-intel-3
Image: sutton-wilkes-xenial-amd64-20180528-71
CPU: Intel(R) Pentium(R) CPU 4415U @ 2.30GHz
GPU: 00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:5906] (rev 02)
BIOS: 7TCN13WW(V1.03.03)

Steps:
1. Log in to system
2. Install checkbox via boxer.
3. Run the *_dim_brightness_* before and after suspend.

Actual result:
The case after suspend is always failed, the error info is "Cannot find job with checksum 387fe0166d8a09019a414dc5d822e4826b3e2bc3aeb7f8f22a6350239b1529d7"

Expected result:
Cases {index}_dim_brightness_{vendor}_after_suspend will pass.

Notes:
1. The brightness can be set to min,max and half of the max brightness manually.
2.u@u-INVALID:/sys/class/backlight$ ll
total 0
drwxr-xr-x 2 root root 0 Jun 26 01:29 ./
drwxr-xr-x 68 root root 0 Jun 26 01:29 ../
lrwxrwxrwx 1 root root 0 Jun 26 01:29 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/

u@u-INVALID:/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight$ ls
actual_brightness bl_power brightness device max_brightness power subsystem type uevent

3.u@u-INVALID:~$ sutton-cli -v
INFO:plainbox.config:Loading configuration from ['/etc/xdg/plainbox.conf', '/home/u/.config/plainbox.conf']
INFO:plainbox.secure.providers.v1:Provider initialized com.canonical.ce:oem, version 1.0
INFO:plainbox.secure.providers.v1:Provider initialized certification-client, version 0.34.0
INFO:plainbox.secure.providers.v1:Provider initialized plainbox-provider-checkbox, version 0.45.0
INFO:plainbox.secure.providers.v1:Provider initialized plainbox-provider-resource-generic, version 0.37.0
INFO:plainbox.secure.providers.v1:Provider initialized plainbox-provider-tpm2, version 1.7.0
INFO:plainbox.secure.providers.v1:Provider initialized com.canonical.plainbox:manifest, version 1.0
INFO:plainbox.secure.providers.v1:Provider initialized com.canonical.plainbox:exporters, version 1.0
INFO:plainbox.secure.providers.v1:Provider initialized com.canonical.plainbox:categories, version 1.0
=========================[ Resume Incomplete Session ]==========================
There is 1 incomplete session that might be resumed