soc/tegra: pmc: Add reboot notifier

soc/tegra: pmc: Add reboot notifier

The Tegra PMC driver implements a restart handler that supports Tegra
specific reboot commands such as placing the device into 'recovery' mode
in order to reprogram the platform. This is accomplished by setting the
appropriate bit in the PMC scratch0 register prior to rebooting the
platform.

For Tegra platforms that support PSCI or EFI, the default Tegra restart
handler is not called and the PSCI or EFI restart handler is called
instead. Hence, for Tegra platforms that support PSCI or EFI, the Tegra
specific reboot commands do not currently work. Fix this by moving the
code that programs the PMC scratch0 register into a separate reboot
notifier that will always be called on reboot.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>