msm: lpm_levels: Adjust latency for Multi core cases

In multi core cases for several cores going in and out of power collapse
the warmboot is serialized at Trust Zone, which means the exit latency
will scale based on the number of cores exiting power collapse.

Adjust for this when chosing a low power mode based on the number of online
cpus.

Change-Id: I4fe137a1bf8596b7da7990845b18ceb8f3d529da
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>