dt-bindings: soc: qcom,aoss-qmp: document the X1E80100 Always-On Subsystem side channel

Document the Always-On Subsystem side channel on the X1E80100 Platform.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231214-x1e80100-soc-qcom-aoss-v1-1-94c46c5182fd@linaro.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>