Crash when suspending system

[pdunaj]

Describe the bug
We enabled watchdog. Now when system goes to sleep crash happens.

To Reproduce
Steps to reproduce the behavior:
Enable watchdog in a application that uses power management. Wait for it. Observe crash when sys_pm_suspend_devices is called.

Expected behavior
System should just go to sleep.

Impact
Showstopper.

Screenshots or console output
N/A

Environment (please complete the following information):
master

Additional context
N/A

[pdunaj]

When call sys_pm_suspend_devices is executed all devices on the list are suppose to get notifications via registered callbacks. Even if some devices this callback is NULL. See watchdog code.

[pdunaj]

There are some other devices that should either be registered using different api or use device_pm_control_nop.