dt-bindings: clk: Add dt-binding header for RV1126

Add the dt-bindings header for the Rockchip RV1126, that gets shared
between the clock controller and the clock references in the dts.

Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>