mach-tegra: add tegra mpdecision with better hotplug management (needs a lot of work)

Currently done:
Copied over from my pyramid kernel.
Renamed everything according to it's new function.
updated the header.
changed get_rate function to tegra specific one (untested).

What needs to be done:
make it quadcore compatible (or cpu number independent)
lp cluster switching
finetuning
etc...

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>