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>
         * 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;