media: dt-bindings: qcom,msm8996-venus: document interconnects

Venus on Qualcomm MSM8996 defines interconnects:

  apq8096-db820c.dtb: video-codec@c00000: Unevaluated properties are not allowed ('interconnect-names', 'interconnects' were unexpected)

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>