net: Don't keep around original SKB when we software segment GSO frames.

Just maintain the list properly by returning the head of the remaining
SKB list from dev_hard_start_xmit().

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

diff --cc include/linux/netdevice.h
Simple merge

diff --cc net/core/dev.c
Simple merge

diff --cc net/sched/sch_generic.c
Simple merge