dt-bindings: soc: sophgo: add RTC support for Sophgo CV1800 series

Add RTC devicetree binding for Sophgo CV1800 series SoC. The device is
called RTC, but contains control registers of other HW blocks in its
address space, most notably of Power-on-Reset (PoR) module, DW8051 IP
(MCU core), accompanying SRAM, hence putting it in SoC subsystem.

Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Inochi Amaoto <inochiama@gmail.com>
Link: https://lore.kernel.org/r/20250315224921.3627852-2-alexander.sverdlin@gmail.com


Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Signed-off-by: Chen Wang <wangchen20@iscas.ac.cn>