libusbhost: Added usb_device_get_unique_id

Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/include/usbhost/usbhost.h b/include/usbhost/usbhost.h
index e7a6127..d67437b 100644
--- a/include/usbhost/usbhost.h
+++ b/include/usbhost/usbhost.h
@@ -57,6 +57,11 @@
  */
 const char* usb_device_get_name(struct usb_device *device);
 
+/* Returns a unique ID for the device.  Currently this is generated from the
+ * dev_name path.
+ */
+int usb_device_get_unique_id(struct usb_device *device);
+
 /* Returns the USB vendor ID from the device descriptor for the USB device */
 uint16_t usb_device_get_vendor_id(struct usb_device *device);