drm/etnaviv: Optimize error handling in etnaviv_gem_new_userptr()

Refactor this function implementation so that the
drm_gem_object_unreference_unlocked() function will only be called once
in case of a failure according to the Linux coding style recommendation
for centralized exiting of functions.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[seanpaul tweaked subject]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/4af34ce6-62c6-7966-1ae3-0877d5ac909d@users.sourceforge.net

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -913,15 +913,12 @@ int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_file *file,
 	get_task_struct(current);
 
 	ret = etnaviv_gem_obj_add(dev, &etnaviv_obj->base);
-	if (ret) {
-		drm_gem_object_unreference_unlocked(&etnaviv_obj->base);
-		return ret;
-	}
+	if (ret)
+		goto unreference;
 
 	ret = drm_gem_handle_create(file, &etnaviv_obj->base, handle);
-
+unreference:
 	/* drop reference from allocate - handle holds it now */
 	drm_gem_object_unreference_unlocked(&etnaviv_obj->base);
-
 	return ret;
 }