mwifiex: Add module parameter for regdomain

Allow a regulatory domain country code to be specified at boot
using a module argument.  This overrides the firmware regulatory
mode.

This patch also enables uAP to operate in 11a mode with hostapd.

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