musb_virthub: use USB_DT_HUB

Fix  using the  bare number to set the 'bDescriptorType' field of the Hub
Descriptor while the value  is #define'd in <linux/usb/ch11.h>.
Signed-off-by: NSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_virthub.c

@@ -345,7 +345,7 @@ int musb_hub_control(
 		struct usb_hub_descriptor *desc = (void *)buf;
 
 		desc->bDescLength = 9;
-		desc->bDescriptorType = 0x29;
+		desc->bDescriptorType = USB_DT_HUB;
 		desc->bNbrPorts = 1;
 		desc->wHubCharacteristics = cpu_to_le16(
 			HUB_CHAR_INDV_PORT_LPSM /* per-port power switching */