dt-bindings: remoteproc: qcom,nord-pas: Document Nord PAS

Add a dedicated binding for the Qualcomm Nord SoC PAS devices: ADSP
and CDSPs. Nord ADSP uses CX and MX power domains while the CDSPs
add an NSP domain on top of that.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Shawn Guo <shengchao.guo@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260729023508.879752-3-shengchao.guo@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>