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.h

@@ -44,7 +44,8 @@ struct rcar_gen3_cpg_pll_config {
 
 struct clk *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);
 int rcar_gen3_cpg_init(const struct rcar_gen3_cpg_pll_config *config,
 		       unsigned int clk_extalr, u32 mode);