USB: usbtest.c: length, sglen and vary are unsigned, so cannot be negative

length, sglen and vary are unsigned, so cannot be negative

see
vi drivers/usb/misc/usbtest.c +18
struct usbtest_param {
...
unsigned iterations;
unsigned length;
unsigned vary;
unsigned sglen;
...
};

Signed-off-by: Roel Kluin <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/misc/usbtest.c

···
 	if (code != USBTEST_REQUEST)
 		return -EOPNOTSUPP;
 
-	if (param->iterations <= 0 || param->length < 0
-			|| param->sglen < 0 || param->vary < 0)
+	if (param->iterations <= 0)
 		return -EINVAL;
 
 	if (mutex_lock_interruptible(&dev->lock))