media: dt-bindings: media: cal: convert binding to yaml

Convert ti-cal.txt to ti,cal.yaml.
Add ti,cal.yaml to the MAINTAINERS file.

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>