cpu_pm: Add level to the cluster pm notification

Cluster pm notifications without level information increases difficulty
and complexity for the registered drivers to figure out when the last
coherency level is going into power collapse.

Send notifications with level information that allows the registered
drivers to easily determine the cluster level that is going in/out of
power collapse.

There is an issue with this implementation. GIC driver saves and
restores the distributed registers as part of cluster notifications. On
newer platforms there are multiple cluster levels are defined (e.g l2,
cci etc). These cluster level notofications can happen independently.
On MSM platforms GIC is still active while the cluster sleeps in idle,
causing the GIC state to be overwritten with an incorrect
previous state
of the interrupts. This leads to a system hang. Do not save and restore
on any L2 and higher cache coherency level sleep entry and exit.

Change-Id: I31918d6383f19e80fe3b064cfaf0b55e16b97eb6
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>