dt-bindings: tegra: Convert Tegra PMC bindings to YAML

This patch converts text based Tegra PMC bindings document to YAML
schema for performing dt validation.
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>