There is no very easy way - what you can try to do is:
- read compile [LibreELEC]
- download source from the branch you want (e.g. git clone https://github.com/LibreELEC/LibreELEC.tv -b libreelec-8.2
- download patch to projects/Odroid_C2/patches/linux
- build kernel ARCH=aarch64 PROJECT=Odroid_C2 ./scripts/build linux
Keep in mind that this involves building whole toolchain which takes time when you build for the first time.