ARM: tegra: Make outer_disable() open-coded

The outer_disable() of Tegra's suspend code is open-coded now since
that helper produces spurious warning message about secondary CPUs being
online when CPU enters into LP2 from cpuidle. The secondaries are actually
halted by the cpuidle driver on entering into LP2 idle-state, but the
online status is not touched by the cpuidle. This fixes a storm of
warnings once LP2 idling state is enabled on Tegra30. The outer_disable()
helper has sanity checks for interrupts and secondary CPUs being disabled
and we are pretty confident about the interrupts state during of CPU
idling / system suspend. The rail-off status check is added in this patch
as equivalent for the "num_online_cpus() > 1".

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>