dt-bindings: clk: Add dt-binding header for RK3588

Add the dt-bindings header for the Rockchip RK3588, that gets
shared between the clock controller and the clock references
in the dts.

commit <f204a60e545c> ("dt-bindings: clock: add rk3588 clock
definitions")

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