Merge branch 'net-af_packet-be-careful-when-expanding-mac-header-size'

Eric Dumazet says:

====================
net: af_packet: be careful when expanding mac header size

A recent regression in af_packet needed a preliminary debug patch,
which will presumably be useful for next bugs hunting.

The af_packet fix is to make sure MAC headers are contained in
skb linear part, as GSO stack requests.

v2: CONFIG_DEBUG_NET depends on CONFIG_NET to avoid compile
   errors found by kernel bots.
====================

Link: https://lore.kernel.org/r/20220602161859.2546399-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>