dt-bindings: power: add Amlogic S6 S7 S7D power domains

Add devicetree binding document and related header file for
Amlogic S6 S7 S7D secure power domains.

Signed-off-by: hongyu.chen1 <hongyu.chen1@amlogic.com>
Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250822-pm-s6-s7-s7d-v1-1-82e3f3aff327@amlogic.com


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