wil6210: prefetch head of packet

As soon as skb is ready to be reaped, prefetch 1-st cache line.
This accelerates data access that is performed later, during the
packet classification by the driver and IP stack.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: 1cbbcb08c786964a16773c39f2536f1923c73c58
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Liron Kuch <lkuch@codeaurora.org>