net/tls: handle MSG_EOR for tls_device TX flow

tls_push_data() MSG_MORE, but bails out on MSG_EOR.
Seeing that MSG_EOR is basically the opposite of MSG_MORE
this patch adds handling MSG_EOR by treating it as the
absence of MSG_MORE.
Consequently we should return an error when both are set.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230726191556.41714-3-hare@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>