ARM: tegra: avoid more operations in non-secure world

ARM: tegra: avoid more operations in non-secure world

A secure monitor that runs before U-Boot, and hence causes U-Boot to run
in non-secure world, must implement a few operations that U-Boot
otherwise implements when running in secure world. Fix U-Boot to skip
these operations when running in non-secure world. In particular:

- The secure monitor must provide the LP0 resume code and own LP0
  configuration in order to maintain security, so must initialize all
  the PMC scratch registers used by the boot ROM during LP0 resume.
  Consequently, U-Boot should not attempt to clear those registers,
  since the register accesses will fail or cause an error.

- The secure monitor owns system security, and so is responsible for
  configuring security-related items such as the VPR.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>