Extend the SCP binding to describe the MT8195 dual-core SCP.

Under different applications, the MT8195 SCP can be used as single-core
or dual-core. This change keeps the single-core definitions and
adds new definitions for the dual-core use case.
Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230901080935.14571-4-tinghan.shen@mediatek.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>