qcacmn: Add support to send wifi down notification

Add command to send wifi down indication when MBSS
feature is enabled.

Change-Id: Ife842dcf8704a97aba848234ddf7b4ddb2a0cc3c

dp/inc/cdp_txrx_stats_struct.h

@@ -1747,6 +1747,8 @@ enum _ol_ath_param_t {
 	OL_ATH_PARAM_DCS_RE_ENABLE_TIMER = 406,
 	/* Enable/disable Rx lite monitor mode */
 	OL_ATH_PARAM_RX_MON_LITE = 407,
+	/* wifi down indication used in MBSS feature */
+	OL_ATH_PARAM_WIFI_DOWN_IND = 408,
 };
 
 /* Enumeration of PDEV Configuration parameter */