sh: ms7724se: Add runtime PM support for FSI

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>