drm: Correct arguments to list_tail_add in create blob ioctl

Arguments passed to list_add_tail were reversed resulting in deletion
of old blob property everytime the new one is added.

Fixes

commit e2f5d2ea479b9b2619965d43db70939589afe43a
Author: Daniel Stone <daniels@collabora.com>
Date:   Fri May 22 13:34:51 2015 +0100

    drm/mode: Add user blob-creation ioctl

Signed-off-by: Maneet Singh <mmaneetsingh@nvidia.com>
[seanpaul tweaked commit subject a little]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Cc: stable@kernel.org # v4.2
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/drm_crtc.c

@@ -4454,7 +4454,7 @@ int drm_mode_createblob_ioctl(struct drm_device *dev,
 	 * not associated with any file_priv. */
 	mutex_lock(&dev->mode_config.blob_lock);
 	out_resp->blob_id = blob->base.id;
-	list_add_tail(&file_priv->blobs, &blob->head_file);
+	list_add_tail(&blob->head_file, &file_priv->blobs);
 	mutex_unlock(&dev->mode_config.blob_lock);
 
 	return 0;