qcacld-3.0: Fix race condition on SAP close and driver exit

When hostapd close and wlan driver unload are happening in parallel
in different context, there could be a race condition in closing
adapter SAP context resulting in crash. Update to fix the crash
by protecting SAP close functions with lock.

Change-Id: I457b765d4932ad2c321fbc7e02f6ab4f289abb10
CRs-fixed: 2014663

core/hdd/src/wlan_hdd_main.c

@@ -3969,9 +3969,9 @@ QDF_STATUS hdd_stop_adapter(hdd_context_t *hdd_ctx, hdd_adapter_t *adapter,
 			qdf_mem_free(adapter->sessionCtx.ap.beacon);
 			adapter->sessionCtx.ap.beacon = NULL;
 		}
-		mutex_unlock(&hdd_ctx->sap_lock);
 		if (true == bCloseSession)
 			hdd_wait_for_sme_close_sesion(hdd_ctx, adapter);
+		mutex_unlock(&hdd_ctx->sap_lock);
 		break;
 	case QDF_OCB_MODE:
 		cdp_clear_peer(cds_get_context(QDF_MODULE_ID_SOC),