[media] bdisp: update MAINTAINERS

Add entry for the bdisp driver to the MAINTAINERS file.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>