cpuidle: tegra: Squash Tegra30 driver into the common driver

Tegra20 and Terga30 SoCs have common C1 and CC6 idling states and thus
share the same code paths, there is no point in having separate drivers
for a similar hardware. This patch merely moves functionality of the old
driver into the new, although the CC6 state is kept disabled for now since
old driver had a rudimentary support for this state (allowing to enter
into CC6 only when secondary CPUs are put offline), while new driver can
provide a full-featured support. The new feature will be enabled by
another patch.

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>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>