set bDeviceClass to CDC_CLASS

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2397 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/drivers/usb/usbdevice/class/cdc_vcom.c

@@ -36,7 +36,7 @@ static struct udevice_descriptor dev_desc =
     USB_DESC_LENGTH_DEVICE,     //bLength;
     USB_DESC_TYPE_DEVICE,       //type;
     USB_BCD_VERSION,            //bcdUSB;
-    0x00,                       //bDeviceClass;
+    USB_CLASS_CDC,              //bDeviceClass;
     0x00,                       //bDeviceSubClass;
     0x00,                       //bDeviceProtocol;
     0x40,                       //bMaxPacketSize0;