Enable ubifs_replay_journal during mount_ubifs, which was
disabled before.
This commit fix an issue with unrecoverable ubifs volumes
after power cut.
Therefor the gc.c is imported now from 1860e37 Linux 3.15
hs: added SPDX-License-Identifier for fs/ubifs/gc.c
Signed-off-by: Anton Habegger <anton.habegger@gmail.com>
