ARM: shmobile: mackerel: switch to using pm-rmobile API

This patch switches mackerel platform to use pm-rmobile base common API.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>