remoteproc: mediatek: Revise SCP rproc initialization flow for multi-core SCP

remoteproc: mediatek: Revise SCP rproc initialization flow for multi-core SCP

This is the 2nd preliminary step for probing multi-core SCP.
Initialization of configuration and L1TCM registers is extracted
to only performed once on multi-core SCP. The rest of remoteproc
initialization procedure is similar for both single and multi-core
SCP and is applied to each core.

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/20230901080935.14571-7-tinghan.shen@mediatek.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>