usb gadget: uvc: uvc_request_data::length field must be signed

The field is used to pass the UVC request data length, but can also be
used to signal an error when setting it to a negative value. Switch from
unsigned int to __s32.

Reported-by: Fernandez Gonzalo <gfernandez@copreci.es>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
index bc78c60..ca4e03a 100644
--- a/drivers/usb/gadget/uvc.h
+++ b/drivers/usb/gadget/uvc.h
@@ -28,7 +28,7 @@
 
 struct uvc_request_data
 {
-	unsigned int length;
+	__s32 length;
 	__u8 data[60];
 };