UPSTREAM: clk: rockchip: add dt-binding header for rk3228

UPSTREAM: clk: rockchip: add dt-binding header for rk3228

Add the dt-bindings header for the rk3228, that gets shared between
the clock controller and the clock references in the dts.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/mmind/linux-rockchip.git
v4.8-shared/clkids commit abf1296599fd679ece61a6c145cc7ee0c490e573)

Change-Id: Id164aa064046276f22dc763c746e9e85c344cd81
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>