rtem.Bityutskiy@nokia.com> 1197889749 +0200
committer Artem Bityutskiy <Artem.Bityutskiy@nokia.com> 1198689315 +0200

UBI: get device when opening volume

When a volume is opened, get its kref via get_device() call.
And put the reference when closing the volume. With this, we
may have a bit saner volume delete.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>