remoteproc: mediatek: Probe SCP cluster on single-core SCP

remoteproc: mediatek: Probe SCP cluster on single-core SCP

This is the 3rd preliminary step for probing multi-core SCP.
Rewrite the probing flow of single-core SCP to adapt with the 'cluster'
concept needed by the multi-core SCP. The SCP core object(s)
is maintained at the cluster list.

Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230901080935.14571-8-tinghan.shen@mediatek.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>