offload.c: do_forward6() pull less

This is to avoid kernel fault due to UDPv6 GRO FRAGLIST collapse
(by virtue of pulling more than udp packet's payload).

Bug: 333849117
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I619316eab1cff3103a3d972682e4cb12de8fca8e
1 file changed