qcacld-3.0: Remove unnecessary assertion in SAP callback

Propagation from qcacld-2.0 to qcacld-3.0

In random testing cases, the SAP close may be called even before the BSS
is started. In such cases the SAP callback may not have been registered
and such scenarios may lead to unnecessary assertion. Just returning an
errror should do.

Remove the assert but retain the error notification.

Change-Id: Ief9ea45d2d7f3d910766e73a9e0dca5e34c85905
CRs-Fixed: 2121720

core/sap/src/sap_fsm.c

@@ -2306,7 +2306,6 @@ QDF_STATUS sap_signal_hdd_event(struct sap_context *sap_ctx,
 
 	/* Format the Start BSS Complete event to return... */
 	if (NULL == sap_ctx->pfnSapEventCallback) {
-		QDF_ASSERT(0);
 		return QDF_STATUS_E_FAILURE;
 	}
 	if (NULL == hal) {