dt-bindings: power: add Amlogic T7 power domains

Add devicetree binding document and related header file for
Amlogic T7 secure power domains.

Signed-off-by: xianwei.zhao <xianwei.zhao@amlogic.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Lucas Tanure <tanure@linux.com>
Link: https://lore.kernel.org/r/20230911025223.3433776-5-xianwei.zhao@amlogic.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>