ARM: tegra: Add Tegra124 PMU support

This patch modifies the device tree for Tegra124 based devices to enable
the Cortex A15 PMU. The interrupt numbers are taken from NVIDIA Tegra K1
TRM (DP-06905-001_v03p). This patch was tested on a Jetson TK1.

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>