don't turn on/off libusb debugging

hardware/saleae-logic/saleae-logic.c

@@ -303,7 +303,6 @@ static int hw_init(char *deviceinfo)
 		g_warning("Failed to initialize USB.");
 		return 0;
 	}
-	libusb_set_debug(usb_context, 3);
 
 	/* Find all Saleae Logic devices and upload firmware to all of them. */
 	devcnt = 0;

hardware/zeroplus-logic-cube/gl_usb.c

@@ -151,8 +151,6 @@ int gl_open(int vid)
 	if (ret < 0)
 		return GL_ELIBUSB;
 
-	libusb_set_debug(NULL, 0);
-
 	if (libusb_get_device_list(NULL, &devs) < 0) {
 		ret = GL_EOPEN;
 		goto gl_open_error;