usb: chipidea: tegra: Add runtime PM and OPP support

The Tegra USB controller belongs to the core power domain and we're going
to enable GENPD support for the core domain. Now USB controller must be
resumed using runtime PM API in order to initialize the USB power state.
We already support runtime PM for the CI device, but CI's PM is separated
from the RPM managed by tegra-usb driver. Add runtime PM and OPP support
to the driver.

Acked-by: Peter Chen <peter.chen@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>