Staging: wlan-ng: Fix sparse warnings by using appropriate endian types

Fix some sparse warning by using correct endian types in structs and
local variables.
This patch only fix sparse warnings and do not change the logic.

Signed-off-by: Adrien Descamps <adrien.descamps@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>