mwifiex: refactor device dump code to make it generic for usb interface

This patch refactor current device dump code to make it generic
for subsequent implementation on usb interface.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>