ARM: cpu_pm: Add cpu power management notifiers

During some CPU power modes entered during idle, hotplug and
suspend, peripherals located in the CPU power domain, such as
the GIC, localtimers, and VFP, may be powered down.  Add a
notifier chain that allows drivers for those peripherals to
be notified before and after they may be reset.

Signed-off-by: Colin Cross <ccross <at> android.com>
[santosh.shilimkar <at> ti.com: Rebased against 3.1-rc3]
Signed-off-by: Santosh Shilimkar <santosh.shilimkar <at> ti.com>
Tested-by: Kevin Hilman <khilman <at> ti.com>
Change-Id: I6e076344b268869d12033f57321f3e7cf23b05e8
Signed-off-by: Ashwin Chaugule <ashwinc@codeaurora.org>