MAINTAINERS: Avoid using K: for NUMA section

When using K: in MAINTAINERS, false positives makes
get_maintainer.pl not use git history to find contributors. As
those patterns cause lots of false positives they are causing
more harm than good, so remove them.

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-id: 1461164130-3847-1-git-send-email-ehabkost@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>