drm/i915: Suspend GuC prior to GPU Reset during GEM suspend

drm/i915: Suspend GuC prior to GPU Reset during GEM suspend

i915 is currently doing a full GPU reset at the end of
i915_gem_suspend() followed by GuC suspend in i915_drm_suspend(). This
GPU reset clobbers the GuC, causing the suspend request to then fail,
leaving the GuC in an undefined state. We need to tell the GuC to
suspend before we do the direct intel_gpu_reset().

v2: Commit message update. (Chris, Daniele)

Fixes: 584a7ff49df0 ("drm/i915/hsw: Fix GPU hang during resume from S3-devices state")
Cc: Jeff McGee <jeff.mcgee@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1491387710-20553-1-git-send-email-sagar.a.kamble@intel.com
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>