dt-bindings: media: add support for video hardware on QCS615 platform

QCS615 uses the same video core as SC7180.

Therefore, add qcom,qcs615-venus compatible to qcom,sc7180-venus.yaml to
enable video hardware support on QCS615 platform. Make qcom,qcs615-venus
fallback to qcom,sc7180-venus to ensure compatibility with existing
configurations.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Renjiang Han <quic_renjiang@quicinc.com>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>