Refactor the dpm suspend watchdog code and add watchdogs
on resume too. The dpm wachdog prints the stack trace and
reboots the system if a device takes more than 12 seconds
to suspend or resume.
Change-Id: If00c047a17b80bdc13a8426393c698bc450a7347
Signed-off-by: Benoit Goby <benoit@android.com>