arm64: dts: rockchip: add PMIC to rock-5a

This adds PMIC support for the Radxa ROCK 5A

Co-developed-by: shengfei Xu <xsf@rock-chips.com>
Signed-off-by: shengfei Xu <xsf@rock-chips.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230710165228.105983-4-sebastian.reichel@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>