pNFS/files: Fix layoutcommit after a commit to DS

commit 73e6c5d8 upstream.

According to the errata
https://www.rfc-editor.org/errata_search.php?rfc=5661&eid=2751


we should always send layout commit after a commit to DS.

Fixes: bc7d4b8f ("nfs/filelayout: set layoutcommit...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>