dt-bindings: soc: qcom: apr: Make qcom,protection-domain optional again

The protection domain functionality exists only in SoCs starting from
MSM8998 [1], while the APR bindings are also used on older platforms.

Commit 41288c305836 ("ASoC: dt-bindings: qcom,apr: Split services to
shared schema") made the "qcom,protection-domain" required but it
should remain optional to avoid dtbs_check warnings on older platforms,
e.g.:

arch/arm64/boot/dts/qcom/apq8096-db820c.dtb:
apr: service@3: 'qcom,protection-domain' is a required property
From schema: Documentation/devicetree/bindings/soc/qcom/qcom,apr.yaml

[1]: https://lore.kernel.org/all/20200312120842.21991-1-sibis@codeaurora.org/

Fixes: 41288c305836 ("ASoC: dt-bindings: qcom,apr: Split services to shared schema")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221229151648.19839-2-stephan@gerhold.net

ASoC: dt-bindings: qcom,apr: Split services to shared schema

The APR/GPR nodes are organized like:

apr-or-gpr-device-node <- qcom,apr.yaml
apr-gpr-service@[0-9] <- qcom,apr.yaml
service-specific-components <- /schemas/sound/qcom,q6*.yaml

The schema for services (apr-gpr-service@[0-9]) already grows
considerably and is still quite not specific. It allows several
incorrect combinations, like adding a clock-controller to a APM device.
Restricting it would complicate the schema even more. Bringing new
support for sound on Qualcomm SM8450 and SC8280XP SoC would grow it as
well.

Simplify the qcom,apr.yaml by splitting the services to a shared file
which will be:
1. Referenced by qcom,apr.yaml with additionalProperties:true,
2. Referenced by specific bindings for services with
additionalProperties:false (not yet in this commit).

While moving the code, add also required 'reg' and
'qcom,protection-domain' to further constrain the bindings.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221115120235.167812-3-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>