ARM: tegra: cpuidle: add CPU resume function

The CPU suspending on Tegra means CPU power gating. We add a resume
function for taking care the CPUs that resume from power gating status.
This function was been hooked to the reset handler. We take care
everything here before go into kernel.

Be aware of that, you may see the legacy power status "LP2" in the code
which is exactly the same meaning of "CPU power down".

Based on the work by:
Scott Williams <scwilliams@nvidia.com>
Colin Cross <ccross@android.com>
Gary King <gking@nvidia.com>

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>