net: tls: make the offload check helper take skb not socket

All callers of tls_is_sk_tx_device_offloaded() currently do
an equivalent of:

 if (skb->sk && tls_is_skb_tx_device_offloaded(skb->sk))

Have the helper accept skb and do the skb->sk check locally.
Two drivers have local static inlines with similar wrappers
already.

While at it change the ifdef condition to TLS_DEVICE.
Only TLS_DEVICE selects SOCK_VALIDATE_XMIT, so the two are
equivalent. This makes removing the duplicated IS_ENABLED()
check in funeth more obviously correct.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Acked-by: Dimitris Michailidis <dmichail@fungible.com>
Signed-off-by: David S. Miller <davem@davemloft.net>