ARM: tegra: add cpu_disable for hotplug

The Tegra114 could hotplug the CPU0, but the common cpu_disable didn't
support that. Adding a Tegra specific cpu_disable function for it.

Signed-off-by: Joseph Lo <josephl@nvidia.com>
[swarren: adjusted the switch statement to be future-proof]
Signed-off-by: Stephen Warren <swarren@nvidia.com>