clk: renesas: cpg-mssr: Add support to restore core clocks during resume

On R-Car Gen3 systems, PSCI system suspend powers down the SoC, possibly
losing clock configuration.  Hence add a notifier chain that can be used
by core clocks to save/restore clock state during system suspend/resume.

The implementation of the actual clock state save/restore operations is
clock-specific, and to be registered with the notifier chain in the SoC
or family-specific cpg_mssr_info.cpg_clk_register() callback.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

drivers/clk/renesas/rcar-gen3-cpg.c

@@ -265,7 +265,8 @@ static const struct soc_device_attribute cpg_quirks_match[] __initconst = {
 
 struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev,
 	const struct cpg_core_clk *core, const struct cpg_mssr_info *info,
-	struct clk **clks, void __iomem *base)
+	struct clk **clks, void __iomem *base,
+	struct raw_notifier_head *notifiers)
 {
 	const struct clk *parent;
 	unsigned int mult = 1;