sunrpc: add routine for comparing addresses

lockd needs these sort of routines, as does the NFSv4 callback code.

Move lockd's routines into common code and rename them so that they can
be used by others.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 7cb076a..4600c20 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -111,7 +111,7 @@
 	 */
 	chain = &nlm_hosts[nlm_hash_address(ni->sap)];
 	hlist_for_each_entry(host, pos, chain, h_hash) {
-		if (!nlm_cmp_addr(nlm_addr(host), ni->sap))
+		if (!rpc_cmp_addr(nlm_addr(host), ni->sap))
 			continue;
 
 		/* See if we have an NSM handle for this client */
@@ -125,7 +125,7 @@
 		if (host->h_server != ni->server)
 			continue;
 		if (ni->server &&
-		    !nlm_cmp_addr(nlm_srcaddr(host), ni->src_sap))
+		    !rpc_cmp_addr(nlm_srcaddr(host), ni->src_sap))
 			continue;
 
 		/* Move to head of hash chain. */