soc/tegra: pmc: Check device node status property

In early_initcall, check if PMC device is available for use
and avoid accessing PMC resources if the device node status
property is set to disabled.

Signed-off-by: Manish Bhardwaj <mbhardwaj@nvidia.com>
Signed-off-by: Petlozu Pravareshwar <petlozup@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>