Merge branch 'net-gro-remove-network_header-use-move-p-flush-flush_id-calculations-to-l4'

Richard Gobert says:

====================
net: gro: remove network_header use, move p->{flush/flush_id} calculations to L4

The cb fields network_offset and inner_network_offset are used instead of
skb->network_header throughout GRO.

These fields are then leveraged in the next commit to remove flush_id state
from napi_gro_cb, and stateful code in {ipv6,inet}_gro_receive which may be
unnecessarily complicated due to encapsulation support in GRO. These fields
are checked in L4 instead.

3rd patch adds tests for different flush_id flows in GRO.
====================

Link: https://lore.kernel.org/r/20240509190819.2985-1-richardbgobert@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>