v4l2: Runtime PM for SuperH Mobile CEU

This patch modifies the SuperH Mobile CEU driver to support
Runtime PM. Driver callbacks for Runtime PM are empty because
the device registers are always re-initialized after
pm_runtime_get_sync(). The Runtime PM functions replaces the
clock framework module stop bit handling in this driver.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>