x86/speculation/mds: Add sysfs reporting for MDS

x86/speculation/mds: Add sysfs reporting for MDS

Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
CVE-2018-12126
CVE-2018-12127
CVE-2018-12130

(backported from commit bd8651092f9656672e53feb1f8e793a0b960138d)
[tyhicks: Backport to 4.15:
 - Include asm/hypervisor.h from bugs.c for hypervisor_is_type()]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>