Fix misspelt event name in the Class driver USBtoSerial demo, preventing correct operation.

Demos/Device/ClassDriver/USBtoSerial/USBtoSerial.c

@@ -137,7 +137,7 @@ void EVENT_USB_Device_ConfigurationChanged(void)
 }
 
 /** Event handler for the library USB Unhandled Control Request event. */
-void EVENT_USB_Device_UnhandledControlPacket(void)
+void EVENT_USB_Device_UnhandledControlRequest(void)
 {
 	CDC_Device_ProcessControlRequest(&VirtualSerial_CDC_Interface);
 }