ARM: dts: r9a06g032: Add missing '#power-domain-cells'

Without '#power-domain-cells' property, power-domains cannot
be used. This property is noted required in the device-tree
binding.

Add '#power-domain-cells' as needed.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20220422120850.769480-6-herve.codina@bootlin.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>