qcacmn: Enhance DCS event handler to support AWGN event

Handle DCS-AWGN event and take actions accordingly:
For STA mode, if the interference locates on primary 20MHz,
disconnect from AP; otherwise, find a max interference free width
and trigger channel change.
For SAP mode, if the interference locates on primary 20MHz,
try to select a random interference free channel and trigger channel
change (stop SAP if no channel is selected); otherwise, find a max
interference free width and trigger channel change.

Change-Id: I33e79f454b459b12ad84f8b0f3259403037464ee
CRs-Fixed: 2958675

umac/global_umac_dispatcher/lmac_if/inc/wlan_lmac_if_def.h

@@ -210,7 +210,7 @@ struct wlan_target_if_dcs_tx_ops {
  */
 struct wlan_target_if_dcs_rx_ops {
 	QDF_STATUS (*process_dcs_event)(struct wlan_objmgr_psoc *psoc,
-					struct dcs_stats_event *event);
+					struct wlan_host_dcs_event *event);
 };
 #endif