clk: rockchip: add dt-binding header for px30

Add the dt-bindings header for the px30, that gets shared between
the clock controller and the clock references in the dts.
Add softreset ID for px30.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>