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 <[email protected]> and Tom
Warren <[email protected]>.

Signed-off-by: Thierry Reding <[email protected]>
Signed-off-by: Tom Warren <[email protected]>