sh: Use struct syscore_ops instead of sysdevs

Convert the SuperH clocks framework and shared interrupt handling
code to using struct syscore_ops instead of a sysdev classes and
sysdevs for power managment.

This reduces the code size significantly and simplifies it.  The
optimizations causing things not to be restored after creating a
hibernation image are removed, but they might lead to undesirable
effects during resume from hibernation (e.g. the clocks would be left
as the boot kernel set them, which might be not the same way as the
hibernated kernel had seen them before the hibernation).

This also is necessary for removing sysdevs from the kernel entirely
in the future.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>