ARM: tegra: Support TZ-only access to PMC

ARM: tegra: Support TZ-only access to PMC

Some devices may restrict access to the PMC to TrustZone software only.
Non-TZ software can detect this and use SMC calls to the firmware that
runs in the TrustZone to perform accesses to PMC registers.

Note that this also fixes reset_cpu() and the enterrcm command on
Tegra186 where they were previously trying to access the PMC at a wrong
physical address.

Based on work by Kalyani Chidambaram <kalyanic@nvidia.com> and Tom
Warren <twarren@nvidia.com>.

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