staging: wlan-ng: silence incorrect type in argument 1 (different address spaces)

Currently p80211knetdev_do_ioctl use type casting to req->data to prevent
sparse warning while calling memdup_user, instead of type casting it here,
its better to change data type for data inside p80211ioctl_req to include
__user.

Signed-off-by: Ashish Kalra <eashishkalra@gmail.com>
Link: https://lore.kernel.org/r/YI1dKdfBKaSh3J8v@ashish-NUC8i5BEH


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>