ARM: dts: rockchip: rename rk3228.dtsi to rk322x.dtsi

We have the brother chipset that RK3228 and RK3229, they share most
of dts configuration, but there are a number of different features.
In order to develop the future when they are easy to distinguish,
we need them to be independent.

Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>