staging: rtl8723au: Fix sparse warning: cast to restricted __le16

usPtr is used as __le16 *, but was defined as u16 *.
This was reported by sparse as:
drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c:1850:29: warning: cast to
restricted __le16

This patch fixes the type of usPtr.
Signed-off-by: Johannes Postma <jgmpostma@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c

@@ -1838,7 +1838,7 @@ Hal_EfuseParseThermalMeter_8723A(struct rtw_adapter *padapter,
 
 static void rtl8723a_cal_txdesc_chksum(struct tx_desc *ptxdesc)
 {
-	u16 *usPtr = (u16 *) ptxdesc;
+	__le16 *usPtr = (__le16 *)ptxdesc;
 	u32 count = 16;		/*  (32 bytes / 2 bytes per XOR) => 16 times */
 	u32 index;
 	u16 checksum = 0;