net: lan966x: Add port keyset config and callback interface

Implement vcap_operations and enable default port keyset configuration
for each port. Now it is possible actually write/read/move entries in
the VCAP.

Signed-off-by: Horatiu Vultur <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: HoratiuVultur