MAINTAINERS: Add the cdrom-test to John's section

MAINTAINERS: Add the cdrom-test to John's section

The cdrom-test checks various block types - IDE, SCSI and
virtio, so it's a little bit hard to decide where this should
belong to in the MAINTAINERS file. But John volunteered to take
it, so let's put it into the IDE section for now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>