usbtest: fix usbtest compilation error by an unused variable

Approved by:    lwhsu (mentor), markj (mentor)
Sponsored by:   The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D51867

Author: aokblast

tools/tools/usbtest/usb_msc_test.c

@@ -952,7 +952,6 @@ find_usb_endpoints(struct libusb20_device *pdev, uint8_t class,
 	struct libusb20_interface *iface;
 	struct libusb20_endpoint *ep;
 	uint8_t x;
-	uint8_t y;
 	uint8_t z;
 
 	*in_ep = 0;
@@ -966,9 +965,6 @@ find_usb_endpoints(struct libusb20_device *pdev, uint8_t class,
 		return;
 
 	for (x = 0; x != pcfg->num_interface; x++) {
-
-		y = alt_setting;
-
 		iface = (pcfg->interface + x);
 
 		if ((iface->desc.bInterfaceClass == class) &&