PM / devfreq: Improve debug logs

- Add more debug logs
- Change the format out the count logs to use hex instead of decimal to be
  consistent with the rest of the logs
- Fix the type of the count variable from signed to unsigned to do the
  above

Change-Id: I02a2968a3f10ce20ca00618e7aeeac9b9cd52bd3
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>