NFSv4.1: remove GETATTR from ds commits

Any COMMIT compound directed to a data server needs to have the
GETATTR calls suppressed.  We here, make sure the field we are testing
(data->lseg) is set and refcounted correctly.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>