NLM: Move the public declaration of nsm_unmonitor() to lockd.h

Clean up.

Make the nlm_host argument "const," and move the public declaration to
lockd.h.  Add a documenting comment.

Bruce observed that nsm_unmonitor()'s only caller doesn't care about
its return code, so make nsm_unmonitor() return void.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 30a6a9c..38344bf 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -245,6 +245,7 @@
  * Host monitoring
  */
 int		  nsm_monitor(const struct nlm_host *host);
+void		  nsm_unmonitor(const struct nlm_host *host);
 
 /*
  * This is used in garbage collection and resource reclaim