tls: Add function to update the TLS socket configuration

The tx configuration is now stored in ctx->tx_conf.
And sk->sk_prot is updated trough a function
This will simplify things when we add rx
and support for different possible
tx and rx cross configurations.

Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>