Staging: rtl8188eu: Fix sparse warning cast to restricted __le16

This patch fixes the following sparse warnings:
drivers/staging/rtl8188eu/core/rtw_wlan_util.c:1627:25: warning: cast to restricted __le16
by changing the annotations in the struct declaration.

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>