dt-bindings: remoteproc: qcom: adsp: document sm8550 adsp, cdsp & mpss compatible

This documents the compatible for the component used to boot the
aDSP, cDSP and MPSS on the SM8550 SoC.

The SM8550 boot process on SM8550 now requires a secondary "Devicetree"
firmware to be passed along the main Firmware, and the cDSP a new power
domain named "NSP".

A third memory domain for the DSM memory zone is also needed for the MPSS
PAS bindings.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221114-narmstrong-sm8550-upstream-remoteproc-v4-2-54154c08c0b7@linaro.org