Merge branch 'nfp-extend-flower-capabilities-for-GRE-tunnel-offload'

Jakub Kicinski says:

====================
nfp: extend flower capabilities for GRE tunnel offload

Pieter says:

This set extends the flower match and action components to offload
GRE decapsulation with classification and encapsulation actions. The
first 3 patches are refactor and cleanup patches for improving
readability and reusability. Patch 4 and 5 implement GRE decap and
encap functionality respectively.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>