dt-bindings: power: meson-g12a-power: document ISP power domain

Add MIPI ISP power domain ID to the G12A Power domains bindings header

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Tested-by: Daniel Scally <dan.scally@ideasonboard.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231123-topic-amlogic-upstream-isp-pmdomain-v2-1-61f2fcf709e5@linaro.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>