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

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

The difference of single-core SCP and multi-core SCP device tree is
the presence of child device nodes described SCP cores. The SCP
driver populates the platform device and checks the child nodes
to identify whether it's a single-core SCP or a multi-core SCP.

Add the remoteproc instances of multi-core SCP to the SCP cluster list.
When the SCP driver is removed, it cleanup resources by walking
through 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/20230901080935.14571-9-tinghan.shen@mediatek.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>