msm: pm2: Modify PM2 idle statistics maintanace functions

Currently pm2.c idle statistic functions doesn't have a support
for dual core targets. Modify idle statistic functions to know
about the number of CPU's it is running and print the idle
statistical(msm_pm_stats) data accordingly. This makes the code
simple in future where modem is the master and APPS is a multicore
(e.g. 8x25).

Change-Id: I713f7e2f88860486883f7fd122f67e5bf85d3d4d
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>