soc: qcom: Add support for Qualcomm Modem Processing SubSystem DSM memory

The Qualcomm SM8550 SoC Modem Processing SubSystem requires that a memory
region named DSM should be shared with the Application Processor SubSystem.

This adds bindings for this MPSS DSM memory and driver implementation to
share this memory region with the Modem Processing SubSystem.

The MPSS DSM memory must be shared between the APPS SubSystem and the MPSS
SubSystems, for the whole lifetime of the system.

To: Andy Gross <agross@kernel.org>
To: Bjorn Andersson <andersson@kernel.org>
To: Konrad Dybcio <konrad.dybcio@somainline.org>
To: Rob Herring <robh+dt@kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
To: Frank Rowand <frowand.list@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

---
Changes in v3:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v2: https://lore.kernel.org/r/20221114-narmstrong-sm8550-upstream-mpss_dsm-v2-0-f7c65d6f0e55@linaro.org

Changes in v2:
- Fixed the bindings
- Added some precision on the MPSS DSM in commit messages
- Link to v1: https://lore.kernel.org/r/20221114-narmstrong-sm8550-upstream-mpss_dsm-v1-0-158dc2bb6e96@linaro.org

--- b4-submit-tracking ---
# This section is used internally by b4 prep for tracking purposes.
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