[i915_bpo] Sync to v4.2.2

[Timo Aaltonen]

There are a few bugfixes upstream that our backport lacks:

 drm/i915: Fix CSR MMIO address check
 drm/i915: Limit the number of loops for reading a split 64bit register
 drm/i915: Always mark the object as dirty when used by the GPU
 drm/i915: Allow DSI dual link to be configured on any pipe
 drm/i915: Preserve SSC earlier
 drm/i915: Check DP link status on long hpd too

the bottom one fixes one OEM bug which also got a BIOS workaround, but a code fix would be in order for other platforms.

[Timo Aaltonen (tjaalton)]

wily has 4.2.2 already IIRC

[Vanessa Chang (vanessa-chang)]

Tested-by: Vanessa Chang <email address hidden>

Verified the test kernel 3.19.0-31.35+bpo1 (http://koti.kapsi.fi/~tjaalton/skl/)

Test configs:
Intel broadwell UMA graphics
Intel SKL-H graphics
Intel SKL-U graphics

Graphics functions are passed.

One issue was found after kernel updated:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1506746

[Timo Aaltonen (tjaalton)]

the hang was due to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1503655

introduced in -31.35, fixed in -31.36. I'll build another test kernel.

[Vanessa Chang (vanessa-chang)]

Verified Passed 10 times of manual reboot test:

Test kernel :
3.19.0-32.37+bpo1

Test Configs:
Intel broadwell UMA graphics
Intel SKL-H graphics
Intel SKL-U graphics

[Vanessa Chang (vanessa-chang)]

Tested-by: Vanessa Chang <email address hidden>

Verified the test kernel 3.19.0-32.37+bpo1

Test configs:
Intel broadwell UMA graphics
Intel SKL-H graphics
Intel SKL-U graphics

Graphics functions are passed except on video out function with SKL-U

One issue was found after kernel updated on SKL-U
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1514315

[Timo Aaltonen (tjaalton)]

I don't think this is necessary anymore