soundwire: qcom: add support for SoundWire controller

soundwire: qcom: add support for 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.

This patchset adds support to a very basic controller which has been
tested with WCD934x SoundWire controller connected to WSA881x smart
speaker amplifiers.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200113132153.27239-3-srinivas.kandagatla@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>