qcacld-3.0: Add vendor attribute for high RSSI roam trigger threshold

Currently the roam scan high RSSI delta is configured via INI.
Define an attribute to allow user configure high RSSI roam
trigger threshold. STA is expected to trigger roam if the current
connected AP's RSSI gets above this high RSSI threshold. STA's
roam attempt on high RSSI threshold aims to find candidates from
other better Wi-Fi bands.
This attribute value is given priority over the INI.
Use a new service bit WMI_SERVICE_5GHZ_HI_RSSI_ROAM_SUPPORT to
enable high RSSI roam trigger in 5 GHz as well.

Change-Id: Ide48ad2261b603de36bd1b31114b91c3a9d6606f
CRs-Fixed: 3586170

components/mlme/dispatcher/inc/wlan_mlme_public_struct.h

@@ -1963,6 +1963,8 @@ struct fw_scan_channels {
  * @roam_trigger_bitmap: Bitmap of roaming triggers.
  * @sta_roam_disable: STA roaming disabled by interfaces
  * @roam_info_stats_num: STA roaming information cache number
+ * @roam_high_rssi_delta: Delta change in high RSSI at which roam scan is
+ * triggered in 2.4/5 GHz.
  * @early_stop_scan_enable: Set early stop scan
  * @enable_5g_band_pref: Enable preference for 5G from INI
  * @ese_enabled: Enable ESE feature
@@ -2092,6 +2094,7 @@ struct wlan_mlme_lfr_cfg {
 	uint32_t roam_trigger_bitmap;
 	uint32_t sta_roam_disable;
 	uint32_t roam_info_stats_num;
+	uint8_t roam_high_rssi_delta;
 #endif
 	bool early_stop_scan_enable;
 	bool enable_5g_band_pref;