MAINTAINERS: Update s390 vhost entries

MAINTAINERS: Update s390 vhost entries

Commit 7a523d96a0 ("virtio-ccw: move vhost_ccw_scsi to a separate file")
introduced a new file hw/s390x/vhost-scsi-ccw.c, which received a
couple comments [1][2] to update MAINTAINERS that were missed.

Fix that by making the vhost CCW entries a wildcard.

[1] https://lore.kernel.org/r/d8d2bbd5021076bdba444d31a6da74f507baede3.camel@linux.ibm.com/
[2] https://lore.kernel.org/r/87k0c4gb9f.fsf@redhat.com/

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20220525145814.2750501-1-farman@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>