qcacmn: Add 2G channel active dwell time CFG/INI items

Add ini item to configure active dwell time of 2.4GHz band channels,
This will help to reduce AP search failure probability & hence
connection latency in 2.4GHz band channels especially in noisy
condition by increasing active dwell time.

Change-Id: I05259a8f1fd4a5c67da42e516721a01d32fa652e
CRs-Fixed: 2283692

wmi_unified_tlv.c

@@ -2697,6 +2697,7 @@ static QDF_STATUS send_scan_start_cmd_tlv(wmi_unified_t wmi_handle,
 	copy_scan_event_cntrl_flags(cmd, params);
 
 	cmd->dwell_time_active = params->dwell_time_active;
+	cmd->dwell_time_active_2g = params->dwell_time_active_2g;
 	cmd->dwell_time_passive = params->dwell_time_passive;
 	cmd->min_rest_time = params->min_rest_time;
 	cmd->max_rest_time = params->max_rest_time;