NSM: Move nsm_addr() to fs/lockd/mon.c

Clean up: nsm_addr_in() is no longer used, and nsm_addr() is used only in
fs/lockd/mon.c, so move it there.

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