NFSD: Support AF_INET6 in svc_addsock() function

Relax the address family check at the top of svc_addsock() to allow AF_INET6
listener sockets to be specified via /proc/fs/nfsd/portlist.
Signed-off-by: Aime Le Rouzic <aime.le-rouzic@bull.net>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

net/sunrpc/svcsock.c

@@ -1357,7 +1357,7 @@ int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
 
 	if (!so)
 		return err;
-	if (so->sk->sk_family != AF_INET)
+	if ((so->sk->sk_family != PF_INET) && (so->sk->sk_family != PF_INET6))
 		err =  -EAFNOSUPPORT;
 	else if (so->sk->sk_protocol != IPPROTO_TCP &&
 	    so->sk->sk_protocol != IPPROTO_UDP)