nfp: add basic action capabilities to flower offloads

Adds push vlan, pop vlan, output and drop action capabilities
to flower offloads.

Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>