x86/sev: Move SEV compilation units

x86/sev: Move SEV compilation units

A long time ago it was agreed upon that the coco stuff needs to go where
it belongs:

  https://lore.kernel.org/all/Yg5nh1RknPRwIrb8@zn.tnic

and not keep it in arch/x86/kernel. TDX did that and SEV can't find time
to do so. So lemme do it. If people have trouble converting their
ongoing featuritis patches, ask me for a sed script.

No functional changes.

Move the instrumentation exclusion bits too, as helpfully caught and
reported by the 0day folks.

Closes: https://lore.kernel.org/oe-kbuild-all/202406220748.hG3qlmDx-lkp@intel.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202407091342.46d7dbb-oliver.sang@intel.com
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Reviewed-by: Ashish Kalra <ashish.kalra@amd.com>
Tested-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/r/20240619093014.17962-1-bp@kernel.org