bpf/progs/offload.c: disable ipv6 offload for non-gso >pmtu

Bug: 263884894
Bug: 419747540
Test: TreeHugger
Flag: EXEMPT mainline
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Idecc355084220ea5c53924c720c806adab153b5d
2 files changed