qcacld-3.0: Fix FW crash when STA_DISCONNECT in STA only mode

FW crashes when disconnect STA interface in STA only mode, since
sending WDI disable command while it is not enabled yet.
WDI disable should be sent only when STA disconnected while SAP
client is connected.
Fix by adding check if SAP client is connected in prior to send
WDI disable command to FW.

Change-Id: Ia7f46e0567d4d5d6f7efe78be5ab5b007419210d
CRs-fixed: 1068439

core/hdd/src/wlan_hdd_ipa.c

@@ -3776,7 +3776,8 @@ static int __hdd_ipa_wlan_evt(hdd_adapter_t *adapter, uint8_t sta_id,
 				hdd_ipa_uc_handle_last_discon(hdd_ipa);
 		}
 
-		if (hdd_ipa_uc_sta_is_enabled(hdd_ipa->hdd_ctx)) {
+		if (hdd_ipa_uc_sta_is_enabled(hdd_ipa->hdd_ctx) &&
+		    (hdd_ipa->sap_num_connected_sta > 0)) {
 			hdd_ipa_uc_offload_enable_disable(adapter,
 				SIR_STA_RX_DATA_OFFLOAD, 0);
 			vdev_to_iface[adapter->sessionId] = HDD_IPA_MAX_IFACE;