media: dt-bindings: trivial white-space and example cleanup

Minor cleanups without funcitonal impact:
 - There should not be an empty blank line after SPDX tag,
 - Convention is to indent DTS examples in coding style with 2- or
   4-space indentation (4 is preferred),
 - Drop unused labels in DTS examples.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>