net/usb/drivers: Remove useless hrtimer_active check

The code does:

 if (hrtimer_active(&t))
    hrtimer_cancel(&t);

However, hrtimer_cancel() checks if the timer is active, so the
test above is pointless.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>