usb: dwc3: use correct hwparam register for power mgm check

We mask the correct bits within the wrong register. The power
optimization mode is stored hwparam1 register and not in hwparam0.

Reported-by: Partha Basak <p-basak2@ti.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>