qcacld-3.0: Don't stop uninitialized timer

currenyly, hdd_medium_assess_stop_timer is invoked during stop_ap
and congestion report disabled. but init is done during congestion
report enable and based on timer flag. So, Assert will be caused
if timer is destroyed due to congestion report disable then stop
AP comes.

Fix is to add timer enable check and based on it call the stop
timer API.

Change-Id: I192b94a08cd07b2be14b2c75b44b3c6a7634b91a
CRs-Fixed: 3589172

core/hdd/src/wlan_hdd_medium_assess.c

@@ -404,12 +404,14 @@ void hdd_medium_assess_stop_timer(uint8_t pdev_id, struct hdd_context *hdd_ctx)
 	for (i = 0; i < WLAN_UMAC_MAX_RP_PID; i++)
 		interval += medium_assess_info[i].config.interval;
 
-	if (!interval) {
+	if (!interval && timer_enable) {
 		ucfg_mc_cp_stats_reset_pending_req(hdd_ctx->psoc,
 						   TYPE_CONGESTION_STATS,
 						   &info, &pending);
 		qdf_mc_timer_stop(&hdd_medium_assess_timer);
 		hdd_debug("medium assess atimer stop");
+	} else {
+		hdd_debug("medium assess timer already disabled");
 	}
 }