drm_vblank_cleanup() would operate on non-existent dev->vblank
data structure, as failure to allocate that data structure is
what triggers the error path in the first place.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>