sh: CMT: Introduce clocksource/clock events suspend/resume routines

Introduce suspend/resume routines for SH CMT clock event devices and
modify the suspend/resume routines for SH CMT clock sources such that
if those devices belong to a PM domain, the generic PM domains
framework will be notified that the given domain may be turned off
(during system suspend) or that it has to be turned on (during system
resume).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>