NSM: Use sm_name instead of h_name in nsm_monitor() and nsm_unmonitor()

Clean up: Use the sm_name field for reporting the hostname in nsm_monitor()
and nsm_unmonitor(), just as the other functions in fs/lockd/mon.c do.

The h_name field is just a copy of the sm_name pointer.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>