This is a re-implementation of adding clock initialization for
tegra2 and tegra3 automotive devices accroding to Dmitry Osipenko's
feedback on version 1[0].
We have moved the initialization from the clock driver to device
tree, but instead of putting them into a dtsi file, we used
dt overlay to patch the device tree at runtime, we believe the
ability to dynamically detect the chipset and apply the right
settings should be useful according to the discussion[1].
Changes against v1:
- use device tree overlay to introduce the automative clock configs
- enable dt overlay for tegra20/30
- move the condition "soc_is_tegra_auto" to be after applied
clock init table.
[0] https://www.spinics.net/lists/linux-tegra/msg38347.html
[1] https://www.spinics.net/lists/arm-kernel/msg665373.html
