ASoC: dt-bindings: qcom,q6asm: convert to dtschema

Convert Qualcomm Audio Stream Manager (Q6ASM) bindings to DT schema.

The original bindings documented:
1. APR service node with compatibles: "qcom,q6asm" and
   "qcom,q6asm-v<MAJOR-NUMBER>.<MINOR-NUMBER>",
2. actual DAIs child node with compatible "qcom,q6asm-dais".

The conversion entirely drops (1) because the compatible is already
documented in bindings/soc/qcom/qcom,apr.yaml.  The
"qcom,q6asm-v<MAJOR-NUMBER>.<MINOR-NUMBER>" on the other hand is not
used at all - neither in existing DTS, nor in downstream sources - so
versions seems to be fully auto-detectable.

Another change done in conversion is adding "iommus" property, which is
already used in DTS and Linux driver.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220910091428.50418-11-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>