nfp: flower: detect potential pre-tunnel rules

Pre-tunnel rules are used when the tunnel end-point is on an 'internal
port'. These rules are used to direct the tunnelled packets (based on outer
header fields) to the internal port where they can be detunnelled. The
rule must send the packet to ingress the internal port at the TC layer.

Currently FW does not support an action to send to ingress so cannot
offload such rules. However, in preparation for populating the pre-tunnel
table to represent such rules, check for rules that send to the ingress of
an internal port and mark them as such. Further validation of such rules
is left to subsequent patches.

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