qcacld-3.0: Add vendor attribute to include 6 GHz in roam full scan

During the roam scan, if there are no desired APs found in the partial
frequency list, an immediate full scan on all the supported frequencies
is initiated as a fallback. This would include the 6 GHz PSC
frequencies by default.
This attribute allow that behavior to be modified to include PSCs only
if 6 GHz use has been detected in the environment.

Change-Id: I6dc380419f14b920737fd87cd9a487c28364563b
CRs-Fixed: 3351697

components/mlme/dispatcher/inc/wlan_mlme_public_struct.h

@@ -1909,6 +1909,8 @@ struct fw_scan_channels {
  * @roam_ho_delay_config: Roam HO delay value
  * @exclude_rm_partial_scan_freq: Exclude the channels in roam full scan that
  * are already scanned as part of partial scan.
+ * @roam_full_scan_6ghz_on_disc: Include the 6 GHz channels in roam full scan
+ * only on prior discovery of any 6 GHz support in the environment.
  */
 struct wlan_mlme_lfr_cfg {
 	bool mawc_roam_enabled;
@@ -2033,6 +2035,7 @@ struct wlan_mlme_lfr_cfg {
 	uint8_t beaconloss_timeout_onsleep;
 	uint16_t roam_ho_delay_config;
 	uint8_t exclude_rm_partial_scan_freq;
+	uint8_t roam_full_scan_6ghz_on_disc;
 };
 
 /**