arm64: dts: renesas: ebisu: Add PMIC DDR0 Backup Power config

On Ebisu the DDR0 power rail needs to be kept powered when backup mode is
enabled.  Reflect this in the "rohm,ddr-backup-power" property for the
BD9571MWV PMIC node.

The accessory power switch (SW23) is a toggle switch, hence specify
"rohm,rstbmode-level".

Based on advice from Geert Uytterhoeven.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts

@@ -466,6 +466,8 @@ pmic: pmic@30 {
 		#interrupt-cells = <2>;
 		gpio-controller;
 		#gpio-cells = <2>;
+		rohm,ddr-backup-power = <0x1>;
+		rohm,rstbmode-level;
 	};
 };