drm/cma: Cocci spatch "ptr_ret.spatch"

diff -u -p a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -174,10 +174,7 @@ int drm_gem_cma_dumb_create(struct drm_f
 
 	cma_obj = drm_gem_cma_create_with_handle(file_priv, dev,
 			args->size, &args->handle);
-	if (IS_ERR(cma_obj))
-		return PTR_ERR(cma_obj);
-
-	return 0;
+	return PTR_RET(cma_obj);
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);