Staging: rtl8723au: core: Add braces around macro

This patch fixes the following checkpatch warning:
ERROR: Macros with complex values should be enclosed
in parentheses
1535: FILE: drivers/staging/rtl8723au/core/rtw_mlme.c:1535:
Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723au/core/rtw_mlme.c

@@ -1532,7 +1532,8 @@ void rtw_set_scan_deny(struct rtw_adapter *adapter, u32 ms)
 }
 
 #if defined(IEEE80211_SCAN_RESULT_EXPIRE)
-#define RTW_SCAN_RESULT_EXPIRE IEEE80211_SCAN_RESULT_EXPIRE/HZ*1000 -1000 /* 3000 -1000 */
+#define RTW_SCAN_RESULT_EXPIRE  \
+	((IEEE80211_SCAN_RESULT_EXPIRE / (HZ*1000)) - 1000) /* 3000 -1000 */
 #else
 #define RTW_SCAN_RESULT_EXPIRE 2000
 #endif