drm/cirrus: Remove unecessary NULL check in gem_free

The ->gem_free_object never gets called with a NULL pointer, the check
is redundant. Also checking after the upcast allows compilers to elide
it anyway.

Spotted by coverity.

Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/cirrus/cirrus_main.c

@@ -271,8 +271,6 @@ void cirrus_gem_free_object(struct drm_gem_object *obj)
 {
 	struct cirrus_bo *cirrus_bo = gem_to_cirrus_bo(obj);
 
-	if (!cirrus_bo)
-		return;
 	cirrus_bo_unref(&cirrus_bo);
 }