chardev: tcp: let TLS run on chardev context

Now qio_channel_tls_handshake() is ready to receive the context.  Let
socket chardev use it, then the TLS handshake of chardev will always be
with the chardev's context.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180306053320.15401-9-peterx@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

chardev/char-socket.c

@@ -751,7 +751,7 @@ static void tcp_chr_tls_init(Chardev *chr)
                               tcp_chr_tls_handshake,
                               chr,
                               NULL,
-                              NULL);
+                              chr->gcontext);
 }