media: MAINTAINERS: Change CAMSS documentation to use dtschema bindings

Due to the complexity of describing multiple hardware generations
in one document, switch to using separate dt-bindings.

Signed-off-by: Robert Foss <robert.foss@linaro.org>
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>