Add new HID_Device_MillisecondElapsed() function to the HID device Class driver, to move the burden of managing the Idle period of each instance to the library and not the user application.

LUFA/Drivers/USB/Class/Device/HID.c

@@ -184,4 +184,10 @@ void HID_Device_USBTask(USB_ClassInfo_HID_Device_t* const HIDInterfaceInfo)
 	}
 }
 
+void HID_Device_MillisecondElapsed(USB_ClassInfo_HID_Device_t* HIDInterfaceInfo)
+{
+	if (HIDInterfaceInfo->State.IdleMSRemaining)
+	  HIDInterfaceInfo->State.IdleMSRemaining--;
+}
+
 #endif