ARM: tegra: Add tegra_pm_park_secondary_cpu()

This function resembles tegra_cpu_die() of the hotplug code, but
this variant is more suitable to be used for CPU PM because it's made
specifically to be used by cpu_suspend(). In short this function puts
secondary CPU offline, it will be used by the new CPUIDLE driver.

Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Jasper Korten <jja2000@gmail.com>
Tested-by: David Heidelberg <david@ixit.cz>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>