qcacmn: Add ioctl param to retrieve MBSS status

Add parameter to know if MBSS feature is enabled or disabled.
During 'wifi detect', the wireless config file is changed and
there's no way to figure out status of MBSS feature.

Change-Id: Ie56244097fd15efc71213f23e5afcb57188c9386
CRs-fixed: 2531506

dp/inc/cdp_txrx_stats_struct.h

@@ -1740,6 +1740,8 @@ enum _ol_ath_param_t {
 	/* same ssid feature global disable */
 	OL_ATH_PARAM_SAME_SSID_DISABLE = 425,
 #endif
+	/* get MBSS enable flag */
+	OL_ATH_PARAM_MBSS_EN  = 426,
 };
 #endif
 /* Bitmasks for stats that can block */