x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

commit 66332e15f4eae7683b61d5397a2151ca0af7ecfd upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>