media: MAINTAINERS: add include/dt-bindings/media to MEDIA INPUT INFRASTRUCTURE

Maintainers of the directory Documentation/devicetree/bindings/media
are also the maintainers of the corresponding directory
include/dt-bindings/media.

Add the file entry for include/dt-bindings/media to the appropriate
section in MAINTAINERS.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>