ASoC: dt-bindings: wsa8840: Document port mapping property

ASoC: dt-bindings: wsa8840: Document port mapping property

Document port mapping property for wsa884x. Port mapping is required
to be able map correct master ports.

All the device ports are not mapped in same order as master ports, so
there is a need for having static port mapping for WSA codecs.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://patch.msgid.link/20240626-port-map-v2-3-6cc1c5608cdd@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>