Document the new C3 SoC/board device tree bindings.

C3 is an advanced edge AI processor designed for smart IP camera
applications, which does not belong to Meson series.

Therefore, modify the title field accordingly.
Signed-off-by: Kelvin Zhang <kelvin.zhang@amlogic.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230407102704.1055152-1-kelvin.zhang@amlogic.comSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>