LinuxKPI: pm.h add pm_sleep_ptr and DEFINE_SIMPLE_DEV_PM_OPS

Extend pm.h by pm_sleep_ptr and DEFINE_SIMPLE_DEV_PM_OPS().
For the moment this duplicates some parts (as can be seen in the earlier
review I tried to simplify bits but given our implementation this
was easier in the end).

While here and cleanup the SIMPLE_DEV_PM_OPS() bits (white-space only).

MFC after: 3 days
Reviewed by: hselasky
Differential Revision: https://reviews.freebsd.org/D37527