mwifiex: fix version display problem on big endian platforms

It's been observed that wrong firmware version (ex. 66.14.96.p9
instead of 14.66.9.p96) is displayed on big endian platforms.

The problem is fixed here.

Reported-by: Daniel Mosquera <daniel.mosquera@ctag.com>
Tested-by: Daniel Mosquera <daniel.mosquera@ctag.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>