mptcp: Handle TCP_MAXSEG getsockopt in common case

This patch simplifies MPTCP's TCP_MAXSEG getsockopt handling by moving it
to the common case where other TCP options are processed. Previously it
was handled separately after the main switch statement.

The change:

 - Moves TCP_MAXSEG case into the main switch block
 - Removes redundant separate handling
 - Maintains identical functionality

This improves code consistency without altering behavior.

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

Author: Geliang Tang

net/mptcp/sockopt.c

@@ -1404,6 +1404,7 @@ static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 	case TCP_FASTOPEN_CONNECT:
 	case TCP_FASTOPEN_KEY:
 	case TCP_FASTOPEN_NO_COOKIE:
+	case TCP_MAXSEG:
 		return mptcp_getsockopt_first_sf_only(msk, SOL_TCP, optname,
 						      optval, optlen);
 	case TCP_INQ:
@@ -1428,9 +1429,6 @@ static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 		return mptcp_put_int_option(msk, optval, optlen, msk->notsent_lowat);
 	case TCP_IS_MPTCP:
 		return mptcp_put_int_option(msk, optval, optlen, 1);
-	case TCP_MAXSEG:
-		return mptcp_getsockopt_first_sf_only(msk, SOL_TCP, optname,
-						      optval, optlen);
 	}
 	return -EOPNOTSUPP;
 }