tls: rx: don't handle TLS 1.3 in the async crypto callback

Async crypto never worked with TLS 1.3 and was explicitly disabled in
commit 8497ded2 ("net/tls: Disable async decrytion for tls1.3").
There's no need for us to handle TLS 1.3 padding in the async cb.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>