arm64: tegra: Rename top-level regulators

Regulators defined at the top level in device tree are no longer part of
a simple bus and therefore don't have a reg property. Nodes without a
reg property shouldn't have a unit-address either, so drop the unit
address from the node names. To ensure nodes aren't duplicated (in which
case they would end up merged in the final DTB), append the name of the
regulator to the node name.

Signed-off-by: Thierry Reding <treding@nvidia.com>