[Intel-gfx] Fixes that failed to backport to v4.12-rc1

[Jani Nikula]

Continuing [1] for v4.12-rc1

The following commits have been marked as Cc: stable or fixing something
in v4.12-rc1 or earlier, but failed to cherry-pick to
drm-intel-fixes. Please see if they are worth backporting, and please do
so if they are.

BR,
Jani.

e6ba9992de6c ("drm/i915: Differentiate between sw write location into ring and last hw read")
73cc0b9aa9af ("drm/i915: Do not sync RCU during shrinking")



[1] http://mid.mail-archive.com/87lgs9dugv.fsf@intel.com

-- 
Jani Nikula, Intel Open Source Technology Center