drm/i915: Don't clobber crtc->fb when queue_flip fails
commit
4a35f83b2b7c6aae3fc0d1c4554fdc99dc33ad07 upstream.
Restore crtc->fb to the old framebuffer if queue_flip fails.
While at it, kill the pointless intel_fb temp variable.
v2: Update crtc->fb before queue_flip and restore it back
after a failure.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-and-Tested-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>