nfp: bpf: remove packet marking support

Temporarily drop support for skb->mark.  We are primarily focusing
on XDP offload, and implementing skb->mark on the new datapath has
lower priority.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>