net/tls: Use tcp_read_sock() instead of ops->read_sock()

TLS resets the protocol operations, so the read_sock() callback might
be changed, too.
In this case using sock->ops->readsock() in tls_strp_read_copyin() will
enter an infinite recursion if the read_sock() callback is calling
tls_rx_rec_wait() which will call into sock->ops->readsock() via
tls_strp_read_copyin().
But as tls_strp_read_copyin() is supposed to produce data from the
consumed socket and that socket is always a TCP socket we can call
tcp_read_sock() directly without having to deal with callbacks.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230726191556.41714-5-hare@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>