tz: Add power collapse debug info

Added power collapse entry (pc_entry_cnt) and power collapse exit
(pc_exit_cnt) count for various CPU.
Renamed the generic entry_cnt/exit_cnt to wb_entry_cnt/wb_exit_cnt
(warm boot entry/exit count) to differentiate from power collapse
case.

Change-Id: I93f2be48a9bbb8fe4c591012430fbc82f20421ab
Signed-off-by: Mona Hossain <mhossain@codeaurora.org>