calipso: unlock rcu before returning -EAFNOSUPPORT

syzbot reported that a recent patch forgot to unlock rcu
in the error path.

Adopt the convention that netlbl_conn_setattr() is already using.

Fixes: 6e9f2df1c550 ("calipso: Don't call calipso functions for AF_INET sk.")
Reported-by: syzbot <[e-mail]>
Signed-off-by: Eric Dumazet <[e-mail]>
Cc: Kuniyuki Iwashima <[e-mail]>
Acked-by: Paul Moore <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/netlabel/netlabel_kapi.c

···
 		break;
 #if IS_ENABLED(CONFIG_IPV6)
 	case AF_INET6:
-		if (sk->sk_family != AF_INET6)
-			return -EAFNOSUPPORT;
+		if (sk->sk_family != AF_INET6) {
+			ret_val = -EAFNOSUPPORT;
+			goto conn_setattr_return;
+		}
 
 		addr6 = (struct sockaddr_in6 *)addr;
 		entry = netlbl_domhsh_getentry_af6(secattr->domain,