drm: i915: Wait for fences on new fb, not old

The previous code would wait for fences on the framebuffer from the old
plane state to complete, rather than the new, so you would see tearing
everywhere. Fix this to wait on the new state before we make it active.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Fixes: 94f050246b42 ("drm/i915: nonblocking commit")
Cc: stable@vger.kernel.org
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161021144454.6288-1-daniels@collabora.com

drivers/gpu/drm/i915/intel_display.c

@@ -14401,7 +14401,7 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
 
 	for_each_plane_in_state(state, plane, plane_state, i) {
 		struct intel_plane_state *intel_plane_state =
-			to_intel_plane_state(plane_state);
+			to_intel_plane_state(plane->state);
 
 		if (!intel_plane_state->wait_req)
 			continue;