arm64: dts: mediatek: mt8188: Describe SCP as a cluster with two cores

The SCP is currently described in the Devicetree as a single-core
processor, but really it is a cluster with two cores. Describe the full
cluster but enable only core0 on the current mt8188 platforms since
that's the only one usable with the upstream firmware.

Co-developed-by: Tinghan Shen <tinghan.shen@mediatek.com>
Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Co-developed-by: Jason Chen <jason-ch.chen@mediatek.corp-partner.google.com>
Signed-off-by: Jason Chen <jason-ch.chen@mediatek.corp-partner.google.com>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20250421-scp-dual-core-mt8390-v2-4-c84117a959a9@collabora.com


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>