Request to add support for SOM3588-CAT

[YANXIAOXIH]

No description provided.

[amazingfate]

Please squash the dts and makefile change into one commit and write good commit message as others: https://github.com/armbian/linux-rockchip/commits/rk-6.1-rkr5/arch/arm64/boot/dts/rockchip.
BTW armbian has toggled to rkr5 branch, which is just set as defaut branch of this repo.

[YANXIAOXIH]

请将 dts 和 makefile 更改压缩为一个提交，并像其他人一样编写良好的提交消息：https://github.com/armbian/linux-rockchip/commits/rk-6.1-rkr5/arch/arm64/boot/dts/rockchip。顺便说一句，armbian 已经切换到了 rkr5 分支，它只是被设置为这个仓库的默认分支。

Thanks for informing me, I'll reapply