x86 MM handling code changes for v6.7:

 - Add new NX-stack self-test
 - Improve NUMA partial-CFMWS handling
 - Fix #VC handler bugs resulting in SEV-SNP boot failures
 - Drop the 4MB memory size restriction on minimal NUMA nodes
 - Reorganize headers a bit, in preparation to header dependency reduction efforts
 - Misc cleanups & fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>