USB: usbtest.c: unsigned retval makes ctrl_out return 0 in case of error

In my quest to try and figure out why test 14 (control write) doesn't
work with my EZ-USB board, I noticed that sometimes testusb reported
no error even though the kernel log complained "byte 0 is 0 not 2" etc.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/usbtest.c

@@ -1242,7 +1242,8 @@ static int halt_simple (struct usbtest_dev *dev)
 static int ctrl_out (struct usbtest_dev *dev,
 		unsigned count, unsigned length, unsigned vary)
 {
-	unsigned		i, j, len, retval;
+	unsigned		i, j, len;
+	int			retval;
 	u8			*buf;
 	char			*what = "?";
 	struct usb_device	*udev;