msm: platsmp-8625: Add cold_boot_done as per_cpu variable

cold_boot_done is declared as an ordinary variable, and useful for
single secondary cpu, right now. It will not work in the scenarios
where we have more than two cores in the system. Usage of per-cpu
variable will make the code more generic for multi-core environment.

Change-Id: I4b2480243b2adaadf5c5a2a3534f66faebd87553
Signed-off-by: tirupathireddy <tirupath@codeaurora.org>