dt-bindings: remoteproc: mediatek: Add interrupts property to mtk,scp

The SCP node can have an associated interrupt. Add a property for it.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220225225854.81038-2-nfraprado@collabora.com