They _could_ in theory post the (no doubt) Perl scripts that generate those headers from the HDL along with the relevant source files, but I imagine that would be a _very_ hard sell. And probably not much more helpful to the kernel, as no one reads those headers anyways, and the compile time will not improve by shuffling where the generation step happens.
It may be more practical to rework the scripts to try to find ways to reduce the verbosity and redundancy. The actual .c driver code probably doesn't need every copy of every lines in all those .h files.
The generators themselves probably not, but the definition of all those registers is from hardware. These kind of code generators convert input source files that describe the hardware into C header files for the software.
But I expect AMD would be skittish about open-sourcing anything that could even remotely be construed as HDL, even if it's just dry lists of registers. Open sourcing the drivers is one thing, but the hardware itself is another.
It may be more practical to rework the scripts to try to find ways to reduce the verbosity and redundancy. The actual .c driver code probably doesn't need every copy of every lines in all those .h files.