nfsd: Add quotes to client info 'callback address'

The 'callback address' in client_info_show is output without quotes
causing yaml parsers to fail on processing IPv6 addresses.
Adding quotes to 'callback address' also matches that used by
the 'address' field.
Signed-off-by: Mark Grimes <mark.grimes@ixsystems.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -2692,7 +2692,7 @@ static int client_info_show(struct seq_file *m, void *v)
 			clp->cl_nii_time.tv_sec, clp->cl_nii_time.tv_nsec);
 	}
 	seq_printf(m, "callback state: %s\n", cb_state2str(clp->cl_cb_state));
-	seq_printf(m, "callback address: %pISpc\n", &clp->cl_cb_conn.cb_addr);
+	seq_printf(m, "callback address: \"%pISpc\"\n", &clp->cl_cb_conn.cb_addr);
 	seq_printf(m, "admin-revoked states: %d\n",
 		   atomic_read(&clp->cl_admin_revoked));
 	drop_client(clp);