staging: wlan-ng: fix invalid assignment warning

p80211_hdr->frame_control is u16, change to __le16
to satisfy sparse warning:

wlan-ng/prism2sta.c:253:43: warning: invalid assignment: |=
wlan-ng/prism2sta.c:253:43:    left side has type unsigned short
wlan-ng/prism2sta.c:253:43:    right side has type restricted __le16

Fixes: 6277fbf ("staging: wlan-ng: Remove pointless a3/a4 union")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Aakash Hemadri <aakashhemadri123@gmail.com>
Link: https://lore.kernel.org/r/20210828042949.2276341-1-aakashhemadri123@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/p80211hdr.h

@@ -149,7 +149,7 @@
 /* Generic 802.11 Header types */
 
 struct p80211_hdr {
-	u16	frame_control;
+	__le16	frame_control;
 	u16	duration_id;
 	u8	address1[ETH_ALEN];
 	u8	address2[ETH_ALEN];