qcom: pm: update warmboot code for cluster architecture

Current warmboot code is designed for only single cluster
configuration. Update the logic to store and read the warmboot
address for cores in multicluster configuration.

Change-Id: Idc18ff35ff8ff9097bee2886c2011cd71c2d6376
Signed-off-by: Venkat Devarasetty <vdevaras@codeaurora.org>