arm64: dts: rockchip: Drop invalid regulator-init-microvolt property

arm64: dts: rockchip: Drop invalid regulator-init-microvolt property

The 'regulator-init-microvolt' property is not currently supported by
any driver, it was simply carried on from downstream kernels.

The problem is also indicated by the following dtbs_check warning:

  rk3588-rock-5b.dtb: pmic@0: regulators:dcdc-reg4: Unevaluated properties are not allowed ('regulator-init-microvolt' was unexpected)

Remove the invalid property from all affected DTS files.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: David Heidelberg <david@ixit.cz>
Link: https://lore.kernel.org/r/20230707162217.675390-1-cristian.ciocaltea@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>