dt-bindings: soc: qcom: apr: Add protection domain bindings

dt-bindings: soc: qcom: apr: Add protection domain bindings

Qualcomm SoCs (starting with MSM8998) allow for multiple protection
domains (PDs) to run on the same Q6 sub-system. This allows for
services like AVS AUDIO to have their own separate address space and
crash/recover without disrupting the other PDs running on the same Q6
ADSP. Add "qcom,protection-domain" bindings to capture the dependencies
between the APR service and the PD on which the apr service runs.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Link: https://lore.kernel.org/r/20200312120842.21991-3-sibis@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>