isp1760-hcd: 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/isp1760/isp1760-hcd.c

@@ -1758,7 +1758,7 @@ static void isp1760_hub_descriptor(struct isp1760_hcd *priv,
 	int ports = HCS_N_PORTS(priv->hcs_params);
 	u16 temp;
 
-	desc->bDescriptorType = 0x29;
+	desc->bDescriptorType = USB_DT_HUB;
 	/* priv 1.0, 2.3.9 says 20ms max */
 	desc->bPwrOn2PwrGood = 10;
 	desc->bHubContrCurrent = 0;