mwifiex: device specific sleep cookie handling for PCIe

This patch adds support for handling of PCIe sleep cookie depending
upon device properties. Some PCIe devices need sleep cookie probing
before accessing HW while some others don't. A new sleep_cookie
variable is defined as part of mwifiex_pcie_card_reg strcture and
set/reset as per device capability.

Sleep cookie is allocated/accessed/freed only when flag sleep_cookie
for this particular device is enabled.

Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>