drivers: sh: pm_runtime implementation needs to suspend and resume devices

If we override the platform bus calls for pm_runtime then we end up
with the calls to the devices' suspend and resume methods ignored
in favour of the bus ones.

Change to calling the pm_runtime calls to suspend and resume the
devices specifically in the drivers/sh/pm_runtime.c implementation
to allow any device that may want to run power management to do so.

Note, all the current sh driver implementations do not use their
own power management code so this is not a major implementation
issues.

This also brings the implementation into line with the versions
used by the Davinci and Keystone PM domain code, so once fully
tested these implementations could be merged together.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>