Fix TCP connection failure when attempting to use a remote host as TNC

[rlaneth]

This PR fixes an issue where TCP connections to remote hosts were failing due to incorrect memory copying of the host address.

The bug was in the open_tcp function where the memcpy parameters were reversed:

// Old (buggy) code:
memcpy(server->h_addr, &serv_addr.sin_addr.s_addr, server->h_length);

// New (fixed) code:
memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);

The fix reverses the parameters so that:

• Source: server->h_addr (the resolved host address)
• Destination: &serv_addr.sin_addr.s_addr (the socket address structure)
• Length: server->h_length (unchanged)

This allows tncattach to properly connect to remote TNCs over TCP as intended.