qcacld-3.0: Add check for iface in wma_setup_install_key_cmd

The host defines the iface ptr with :-
iface = &wma_handle->interfaces[key_params->vdev_id], at line 1588
and if the WLAN_FEATURE_11W, is not enabled , the host sets the
iface->is_waiting_for_key as false , without a NULL check of iface.
Fix is to add a NULL check for iface

Change-Id: I69ed8f881b678458d16f1f74e87e31959c04ec63
CRs-Fixed: 2156921

core/wma/src/wma_mgmt.c

@@ -1807,7 +1807,8 @@ static QDF_STATUS wma_setup_install_key_cmd(tp_wma_handle wma_handle,
 	}
 
 	/* install key was requested */
-	iface->is_waiting_for_key = false;
+	if (iface)
+		iface->is_waiting_for_key = false;
 
 end:
 	qdf_mem_free(params.key_rsc_counter);