mptcp: drop inet6_sk in mptcp_nl_find_ssk

In mptcp_nl_find_ssk(), 'issk' has already been got through inet_sk(). No
need to use inet6_sk() to get 'pinfo' again, just use issk->pinet6 instead.
This patch also drops this 'pinfo' variable.

Signed-off-by: Geliang Tang <[email protected]>

Author: Geliang Tang

net/mptcp/pm_userspace.c

@@ -465,9 +465,7 @@ static struct sock *mptcp_nl_find_ssk(struct mptcp_sock *msk,
 			break;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 		case AF_INET6: {
-			const struct ipv6_pinfo *pinfo = inet6_sk(ssk);
-
-			if (!ipv6_addr_equal(&local->addr6, &pinfo->saddr) ||
+			if (!ipv6_addr_equal(&local->addr6, &issk->pinet6->saddr) ||
 			    !ipv6_addr_equal(&remote->addr6, &ssk->sk_v6_daddr))
 				continue;
 			break;