TCG doesn't support any of the feature flags on FEAT_KVM and
FEAT_C000_0001_EDX feature words, so clear all bits on those feature
words.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>