arm64: dts: rockchip: add rk817 chg to RG353P and RG503

Add support for the internal battery and charger for the Anbernic
RG353P and RG503. Battery values are taken from the BSP Kernel
device tree.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20221028184045.13113-4-macroalpha82@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>