arm64: dts: renesas: ulcb: Add PMIC DDR Backup Power config

On the R-Car Starter Kit Premier/Pro, all of the DDR0, DDR1, DDR0C, and
DDR1C power rails need 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 (SW8) is a momentary switch, hense specify
"rohm,rstbmode-pulse".
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/ulcb.dtsi

@@ -256,6 +256,8 @@
 		#interrupt-cells = <2>;
 		gpio-controller;
 		#gpio-cells = <2>;
+		rohm,ddr-backup-power = <0xf>;
+		rohm,rstbmode-pulse;
 
 		regulators {
 			dvfs: dvfs {