drm/i915: Avoid round-trip via i915 in intel_gt_park

Both in the container_of and getting to gt->awake there is no need to go
via i915 since both the wakeref and awake are members of gt.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190910143823.10686-4-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/gt/intel_gt_pm.c

@@ -56,9 +56,9 @@ static int __gt_unpark(struct intel_wakeref *wf)
 
 static int __gt_park(struct intel_wakeref *wf)
 {
-	struct drm_i915_private *i915 =
-		container_of(wf, typeof(*i915), gt.wakeref);
-	intel_wakeref_t wakeref = fetch_and_zero(&i915->gt.awake);
+	struct intel_gt *gt = container_of(wf, typeof(*gt), wakeref);
+	intel_wakeref_t wakeref = fetch_and_zero(&gt->awake);
+	struct drm_i915_private *i915 = gt->i915;
 
 	GEM_TRACE("\n");