clk: tegra124: add wait_for_reset and disable_clock for tegra_cpu_car_ops

Hook the functions for CPU hotplug support. After the CPU is hot
unplugged, the flow controller will handle to clock gate the CPU clock.
But still need to implement an empty function to avoid warning message.

Cc: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Joseph Lo <josephl@nvidia.com>