drm/cma: Replace PTR_RET with PTR_ERR_OR_ZERO

PTR_RET is now deprecated. Use PTR_ERR_OR_ZERO instead.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/gpu/drm/drm_gem_cma_helper.c

@@ -215,7 +215,7 @@ int drm_gem_cma_dumb_create(struct drm_file *file_priv,
 
 	cma_obj = drm_gem_cma_create_with_handle(file_priv, dev,
 			args->size, &args->handle);
-	return PTR_RET(cma_obj);
+	return PTR_ERR_OR_ZERO(cma_obj);
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);