soc/tegra: pmc: Disable PMC state syncing

Disable PMC state syncing in order to ensure that we won't break older
kernels once device-trees will be updated with the addition of the power
domains. This also allows to apply device-tree PM patches independently
from the driver patches.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>