x86/bugs: Rename MDS machinery to something more generic

From: "Borislav Petkov (AMD)" <bp@alien8.de>

Commit f9af88a3 upstream.

It will be used by other x86 mitigations.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>