With the smsm bindings and driver finally supporting mboxes, switch to
that and stop using apcs as syscon.
Signed-off-by: Luca Weiss <luca@lucaweiss.eu>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240619-smsm-mbox-dts-v1-3-268ab7eef779@lucaweiss.euSigned-off-by: Bjorn Andersson <andersson@kernel.org>