dt-bindings: remoteproc: qcom,smd-edge: Mark qcom,ipc as deprecated

Deprecate the qcom,ipc way of accessing the mailbox in favor of the
'mboxes' property.

Update the example to use mboxes.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240425-qcom-ipc-deprecate-v1-1-a8d8034253ea@z3ntu.xyz


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