qcacld-3.0: Remove legacy congestion stats implementation

Driver has a stats infrastructure and all the stats related
commands are using this infrastructure.

Remove legacy implementation for congestion stats command
as part of cleanup.

Change-Id: Ia8b919ad7cea4f47d5480b9f8e0f4636783ce6c3
CRs-Fixed: 2480246

core/hdd/inc/wlan_hdd_assoc.h

@@ -204,7 +204,6 @@ struct hdd_connection_info {
 	uint32_t roam_count;
 	int8_t signal;
 	int32_t assoc_status_code;
-	uint32_t cca;
 	tCsrSSIDInfo last_ssid;
 	enum csr_akm_type last_auth_type;
 	char auth_time[HDD_TIME_STRING_LEN];