macsec: Enable devices to advertise whether they update sk_buff md_dst during offloads

macsec: Enable devices to advertise whether they update sk_buff md_dst during offloads

Cannot know whether a Rx skb missing md_dst is intended for MACsec or not
without knowing whether the device is able to update this field during an
offload. Assume that an offload to a MACsec device cannot support updating
md_dst by default. Capable devices can advertise that they do indicate that
an skb is related to a MACsec offloaded packet using the md_dst.

Cc: Sabrina Dubroca <[email protected]>
Cc: [email protected]
Fixes: 860ead89b851 ("net/macsec: Add MACsec skb_metadata_dst Rx Data path support")
Signed-off-by: Rahul Rameshbabu <[email protected]>
Reviewed-by: Benjamin Poirier <[email protected]>
Reviewed-by: Cosmin Ratiu <[email protected]>
Reviewed-by: Sabrina Dubroca <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>