dt-bindings: soundwire: add bindings for Qcom controller

dt-bindings: soundwire: add bindings for Qcom controller

This patch adds bindings for Qualcomm soundwire controller.

Qualcomm SoundWire Master controller is present in most Qualcomm SoCs
either integrated as part of WCD audio codecs via slimbus or
as part of SOC I/O.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200113132153.27239-2-srinivas.kandagatla@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>