create imx8-5.3-devkit branch and put it into current images
- create a branch
imx8-5.3-devkitthat currently is the same commit as the imx8-linux-next-dev branch HEAD (but just stays at 5.3-rcX or 5.3 no matter what we do with the -next branch)
- is it ok to drop 5.2 in the build script? I guess so. nothing special about it. all our changes are in 5.3 AFAIK.
- our 5.3 based tree has new features needed for userspace and it adds no value to backport stuff
- 5.3-rcX is basically identical to the 5.3 release and stable enough for us. no need to wait.
- switch from 5.2 to 5.3 in https://source.puri.sm/Librem5/image-builder/blob/master/conf/board#L85
- add a new jenkins kernel build (?) similar to https://arm01.puri.sm/job/Kernel_builds/job/kernel_devkit_linux-next_imx8-5.2-devkit/ ?
- advantage: we can then branch out into a real -next in our main -next branch if one would want to