qed: Fix system crash in ll2 xmit

qed: Fix system crash in ll2 xmit

[ Upstream commit 7c81626a3c37e4ac320b8ad785694ba498f24794 ]

Cache number of fragments in the skb locally as in case
of linear skb (with zero fragments), tx completion
(or freeing of skb) may happen before driver tries
to get number of frgaments from the skb which could
lead to stale access to an already freed skb.

Signed-off-by: Manish Chopra <manishc@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>