dt-bindings: power: Add power-domain header for rv1126

Add power-domain header for RV1126 SoC from description in TRM.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>