drm/i915: Spruce up assert_sprites_disabled()

Make assert_sprites_disabled() operational on all platforms where
we currently have sprite support enabled.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed