tools: usb: testusb: Add super-plus speed reporting

Add the ability to detect and print the USB speed as "super-plus" if/when
the kernel reports that speed.

Signed-off-by: Bryan O'Donoghue <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

tools/usb/testusb.c

···
 	USB_SPEED_HIGH,				/* usb 2.0 */
 	USB_SPEED_WIRELESS,			/* wireless (usb 2.5) */
 	USB_SPEED_SUPER,			/* usb 3.0 */
+	USB_SPEED_SUPER_PLUS,			/* usb 3.1 */
 };
 
 /*-------------------------------------------------------------------------*/
···
 	case USB_SPEED_HIGH:		return "high";
 	case USB_SPEED_WIRELESS:	return "wireless";
 	case USB_SPEED_SUPER:		return "super";
+	case USB_SPEED_SUPER_PLUS:	return "super-plus";
 	default:			return "??";
 	}
 }