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.

Suggested-by Ulf Hansson <[email protected]>

Signed-off-by Geert Uytterhoeven <[email protected]>

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This is a dependency for "[PATCH 1/2] PM / genpd: Stop/start devices without pm_runtime_force_suspend/resume()"
(https://www.spinics.net/lists/kernel/msg2696802.html), so perhaps it makes most sense if Rafael takes it through the PM tree?