board: rockchip: Add support for RG353PS to RGxx3

board: rockchip: Add support for RG353PS to RGxx3

Add support for the RG353PS to the Anbernic RGxx3. This device is a
slightly pared down version of the RG353P with no eMMC, no touchscreen,
and only 1GB of RAM.

Refactor board logic so that all supported devices are defined with
ADC values and that future boards can be added by just defining the
board values in the device array.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>