chardev-socket: remove useless if

This trips Coverity, which believes the subsequent qio_channel_create_watch
can dereference a NULL pointer.  In reality, tcp_chr_connect's callers
all have s->ioc properly initialized, since they are all rooted at
tcp_chr_new_client.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>