wlan: Defer scan if back to back scan on STA interface.

If there is scan on STA interface back to back with
time diff nDeferScanTimeInterval, driver will not
issue a new scan. Driver will return previous result to kernel.

CRs-Fixed: 757773
Change-Id: I09e9b23f64d959ef5846096cdae810f84b8a1b97
diff --git a/CORE/HDD/inc/wlan_hdd_main.h b/CORE/HDD/inc/wlan_hdd_main.h
index 714d51f..2ca4506 100644
--- a/CORE/HDD/inc/wlan_hdd_main.h
+++ b/CORE/HDD/inc/wlan_hdd_main.h
@@ -770,6 +770,10 @@
 
    hdd_scan_pending_option_e scan_pending_option;
    tANI_U8 sessionId;
+   /* time to store last station scan done. */
+   v_TIME_t     last_scan_timestamp;
+   tANI_U8 last_scan_channelList[WNI_CFG_VALID_CHANNEL_LIST_LEN];
+   tANI_U8 last_scan_numChannels;
 
 }hdd_scaninfo_t;