staging: r8188eu: Fix sparse warnings in rtw_ieee80211.c

Sparse reports the following:

  CHECK   drivers/staging/rtl8188eu/core/rtw_ieee80211.c
drivers/staging/rtl8188eu/core/rtw_ieee80211.c:1593:14: warning: cast to restricted __le16
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/include/ieee80211.h

@@ -306,8 +306,8 @@ struct ieee_ibss_seq {
 };
 
 struct rtw_ieee80211_hdr {
-	u16 frame_ctl;
-	u16 duration_id;
+	__le16 frame_ctl;
+	__le16 duration_id;
 	u8 addr1[ETH_ALEN];
 	u8 addr2[ETH_ALEN];
 	u8 addr3[ETH_ALEN];
@@ -316,8 +316,8 @@ struct rtw_ieee80211_hdr {
 } __packed;
 
 struct rtw_ieee80211_hdr_3addr {
-	u16 frame_ctl;
-	u16 duration_id;
+	__le16 frame_ctl;
+	__le16 duration_id;
 	u8 addr1[ETH_ALEN];
 	u8 addr2[ETH_ALEN];
 	u8 addr3[ETH_ALEN];
@@ -325,8 +325,8 @@ struct rtw_ieee80211_hdr_3addr {
 } __packed;
 
 struct rtw_ieee80211_hdr_qos {
-	u16 frame_ctl;
-	u16 duration_id;
+	__le16 frame_ctl;
+	__le16 duration_id;
 	u8 addr1[ETH_ALEN];
 	u8 addr2[ETH_ALEN];
 	u8 addr3[ETH_ALEN];
@@ -336,8 +336,8 @@ struct rtw_ieee80211_hdr_qos {
 }  __packed;
 
 struct rtw_ieee80211_hdr_3addr_qos {
-	u16 frame_ctl;
-	u16 duration_id;
+	__le16 frame_ctl;
+	__le16 duration_id;
 	u8 addr1[ETH_ALEN];
 	u8 addr2[ETH_ALEN];
 	u8 addr3[ETH_ALEN];