ASoC: qdsp6: dt-bindings: Add q6afe display_port dt binding

This patch adds bindings required for DISPLAY_PORT_RX
port on AFE.

Signed-off-by: Rohit kumar <rohitkr@codeaurora.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>