ARM: tegra: cpuidle: Handle tick broadcasting within cpuidle core on Tegra20/30

Tegra20/30 drivers do not handle the tick_broadcast_enter() error which
potentially could happen when CPU timer isn't permitted to be stopped.
Let's just move out the broadcasting to the CPUIDLE core by setting the
respective flag in the Tegra20/30 drivers. This patch doesn't fix any
problem because currently tick_broadcast_enter() could fail only on
ARM64, so consider this change as a minor cleanup.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>