[media] MAINTAINERS: add entries for sh_veu and sh_vou V4L2 drivers

sh_vou might be better described by "Odd Fixes," but mark it "Maintained"
for now. sh_veu is a new driver and might see some development in the
future.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>