drm/i915: Remove redundant flip_work->flip_queued_ring

Similar to the patch from John which removed obj->ring.

Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Thomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e216cb7..376ec89 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9132,7 +9132,6 @@
 	if (work->flip_queued_req)
 		i915_gem_request_unreference(work->flip_queued_req);
 	work->flip_queued_req  = NULL;
-	work->flip_queued_ring = NULL;
 	mutex_unlock(&dev->struct_mutex);
 
 	intel_frontbuffer_flip_complete(dev, INTEL_FRONTBUFFER_PRIMARY(pipe));
@@ -9741,10 +9740,9 @@
 		return false;
 
 	if (work->flip_ready_vblank == 0) {
-		if (work->flip_queued_ring) {
-			if (!i915_gem_request_completed(work->flip_queued_req, true))
-				return false;
-		}
+		if (work->flip_queued_req &&
+		    !i915_gem_request_completed(work->flip_queued_req, true))
+			return false;
 
 		work->flip_ready_vblank = drm_vblank_count(dev, intel_crtc->pipe);
 	}
@@ -9910,8 +9908,6 @@
 
 		i915_gem_request_assign(&work->flip_queued_req,
 					obj->last_write_req);
-		work->flip_queued_ring =
-				i915_gem_request_get_ring(obj->last_write_req);
 	} else {
 		ret = dev_priv->display.queue_flip(dev, crtc, fb, obj, ring,
 						   page_flip_flags);
@@ -9920,7 +9916,6 @@
 
 		i915_gem_request_assign(&work->flip_queued_req,
 					intel_ring_get_request(ring));
-		work->flip_queued_ring = ring;
 	}
 
 	work->flip_queued_vblank = drm_vblank_count(dev, intel_crtc->pipe);