usb: usbtest: reduce stack usage in test_queue

Fix the warning: [-Werror=-Wframe-larger-than=]

drivers/usb/misc/usbtest.c: In function 'test_queue':
drivers/usb/misc/usbtest.c:2148:1:
warning: the frame size of 1232 bytes is larger than 1024 bytes

Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Link: https://lore.kernel.org/r/ffa85702-86ab-48d7-4da2-2efcc94b05d3@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/usbtest.c

@@ -2043,14 +2043,18 @@ test_queue(struct usbtest_dev *dev, struct usbtest_param_32 *param,
 	unsigned		i;
 	unsigned long		packets = 0;
 	int			status = 0;
-	struct urb		*urbs[MAX_SGLEN];
+	struct urb		**urbs;
 
 	if (!param->sglen || param->iterations > UINT_MAX / param->sglen)
 		return -EINVAL;
 
 	if (param->sglen > MAX_SGLEN)
 		return -EINVAL;
 
+	urbs = kcalloc(param->sglen, sizeof(*urbs), GFP_KERNEL);
+	if (!urbs)
+		return -ENOMEM;
+
 	memset(&context, 0, sizeof(context));
 	context.count = param->iterations * param->sglen;
 	context.dev = dev;
@@ -2137,13 +2141,17 @@ test_queue(struct usbtest_dev *dev, struct usbtest_param_32 *param,
 	else if (context.errors >
 			(context.is_iso ? context.packet_count / 10 : 0))
 		status = -EIO;
+
+	kfree(urbs);
 	return status;
 
 fail:
 	for (i = 0; i < param->sglen; i++) {
 		if (urbs[i])
 			simple_free_urb(urbs[i]);
 	}
+
+	kfree(urbs);
 	return status;
 }