By default the DSP domains are non secure, add the missing
qcom,non-secure-domain property to mark them as non-secure.

Fixes: d0c061e3 ("arm64: dts: qcom: sm8550: add adsp, cdsp & mdss nodes")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240227-topic-sm8x50-upstream-fastrpc-non-secure-domain-v1-2-15c4c864310f@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>