staging: wlan-ng: Fix sparse warning: cast to restricted __le16.

The same structure is used in both side, so we dont need to cast.
This will fix the following sparse warnings:
drivers/staging/wlan-ng/prism2sta.c:1139:13: warning: cast to restricted __le16
drivers/staging/wlan-ng/prism2sta.c:1150:24: warning: cast to restricted __le16
drivers/staging/wlan-ng/prism2sta.c:1157:37: warning: cast to restricted __le16
drivers/staging/wlan-ng/prism2sta.c:1158:37: warning: cast to restricted __le16
drivers/staging/wlan-ng/prism2sta.c:1159:40: warning: cast to restricted __le16
drivers/staging/wlan-ng/prism2sta.c:1450:31: warning: cast to restricted __le16

Signed-off-by: AbdAllah MEZITI <abdallah.meziti.pro@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>