mwifiex: firmware dump support for w8997 chipset

Current firmware dump solution support w8897 chipset, this
patch extend the exist framework with support for w8997
chipset.

Trigger firmware dump using,
cat /sys/kernel/debug/mwifiex/mlan0/device_dump,
data can be obtain by
cat /sys/class/devcoredump/devcd*/data > data.txt after that.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>