tools: usb: testusb: Add super speed reporting

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

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Link: https://lore.kernel.org/r/20220708115859.2095714-3-bryan.odonoghue@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>