dt-bindings: power: add Amlogic s4 power domains bindings

Add the bindings for the Amlogic Secure power domains, controlling the
secure power domains.

The bindings targets the Amlogic s4, in which the power domains registers
are in secure world.

Signed-off-by: Shunzhou Jiang <shunzhou.jiang@amlogic.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220307025357.1368673-2-shunzhou.jiang@amlogic.com