delete dts since merged upstream, fix backport patch for rkr4

Author: amazingfate

README.md

@@ -1,6 +1,6 @@
 # Armbian images for H68K
 [![image_build](https://github.com/amazingfate/armbian-h68k-images/workflows/Build/badge.svg)](https://github.com/amazingfate/armbian-h68k-images/actions/workflows/build.yml)
 
-This is now a community supported build. The device tree is not in [armbian's repo](https://github.com/armbian/build) by now. Edit rk3588-h68k.dts to modify the device tree.
+This is now a community supported build.
 
 Download: https://github.com/amazingfate/armbian-h68k-images/releases/latest