x86/litf: Introduce vmx status variable

x86/litf: Introduce vmx status variable

Store the effective mitigation of VMX in a status variable and use it to
report the VMX state in the l1tf sysfs file.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142322.433098358@linutronix.de
Orabug: 28220674
CVE: CVE-2018-3620

(cherry picked from commit 72c6d2db64fa18c996ece8f06e499509e6c9a37e)

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Conflicts:
	arch/x86/kvm/vmx.c
	arch/x86/kernel/cpu/bugs.c
Contextual: different content; Changes were done in arch/x86/kernel/cpu/bugs_64.c
instead of arch/x86/kernel/cpu/bugs.c.
__ro_after_init was replaced with __read_mostly for l1tf_vmx_mitigation to avoid
cherry-picking c74ba8b3.