Misc x86 fixes:

 - Follow up fixes for the BHI mitigations code.

 - Fix !SPECULATION_MITIGATIONS bug not turning off
   mitigations as expected.

 - Work around an APIC emulation bug when the kernel is built with
   Clang and run as a SEV guest.

 - Follow up x86 topology fixes.

Note that there's minor cleanups included in the BHI fixes,
which we'd normally delay to the next merge window, but the
BHI mitigations code is new and will be backported widely,
so we thought it would be better to have a unified codebase
at this stage. (Let me know if that assumption is wrong and
I'll rebase it.)

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