net: microchip: sparx5: Let VCAP API validate added key- and actionfields

Add support for validating keyfields and actionfields when they are added
to a VCAP rule.
We need to ensure that the field is not already present and that the field
is in the key- or actionset, if the client has added a key- or actionset to
the rule at this point.

Signed-off-by: Steen Hegelund <steen.hegelund@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>