msm: pm: Add power collapse debug counters support.

Add platform device for PC debug counters. These counter stores the
warmboot entry/exit counters for each core on a non-cacheable always
on IMEM memory. This is a useful feature during debug to understand if
the system has correctly warmbooted after a power collapse.

Usage for core0 debug counters:-
counters at address 0x2A03F664 represent no of times PC attempted.
counters at address 0x2A03F66C represent no of times PC failed.
counters at address 0x2A03F668 represent no of times warm boot happened.
no of PC attemps = PC failures + warm boot entries.

Change-Id: I3f78921f1ddd55967284fb7839a98bdb43efbeb9
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>