DFU Runtime: Add missing return after handling USB standard requests

the same as 479e97e3382f72da1959276d8ec3a9defc5b75f5 but this time for
the runtime, not for DFU.
diff --git a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_runtime.c b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_runtime.c
index b71a572..baae3c4 100644
--- a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_runtime.c
+++ b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_runtime.c
@@ -117,6 +117,7 @@
 	    USBGenericRequest_GetRecipient(request) != USBGenericRequest_INTERFACE) {
 		TRACE_DEBUG("std_ho_usbd ");
 		USBDDriver_RequestHandler(usbdDriver, request);
+		return;
 	}
 
 	switch (g_dfu->state) {