riscv: dts: sophgo: Add SARADC description for Sophgo CV1800B

riscv: dts: sophgo: Add SARADC description for Sophgo CV1800B

Add SARADC node for the Successive Approximation Analog to
Digital Converter used in Sophgo CV1800B SoC.
This patch only adds the active domain controller.

Signed-off-by: Thomas Bonnefille <thomas.bonnefille@bootlin.com>
Reviewed-by: Inochi Amaoto <inochiama@gmail.com>
Link: https://lore.kernel.org/r/20240829-sg2002-adc-v5-3-aacb381e869b@bootlin.com
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>