LU-11925 hsm: attributes aren't updated after RESTORE

LU-11925 hsm: attributes aren't updated after RESTORE

MDS returns file size to a client with UPDATE lock
while file is RELEASED. It isn't cancelled after RESTORE
and the client has old file size after appending data.

Flush update lock after RESTORE completed.

Change-Id: Ib956dbd075691ce5fac1ce552df9519f9fa768e4
Cray-bug-id: LUS-6945
Signed-off-by: Andriy Skulysh <c17819@cray.com>
Reviewed-on: https://review.whamcloud.com/34180
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Sergey Cheremencev <c17829@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>