dmaengine: rcar-dmac: Make DMAC reinit during system resume explicit

The current (empty) system sleep callbacks rely on the PM core to force
a runtime resume to reinitialize the DMAC registers during system
resume.  Without a reinitialization, e.g. SCIF DMA will hang silently
after a system resume on R-Car Gen3.

Make this explicit by using pm_runtime_force_{suspend,resume}() as the
system sleep callbacks instead.  Use SET_LATE_SYSTEM_SLEEP_PM_OPS() as
DMA engines must be initialized before all DMA slave devices.

Fixes: 17218e00

 "PM / genpd: Stop/start devices without pm_runtime_force_suspend/resume()"
Suggested-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>