soc: mediatek: mtk-svs: clean up platform probing

We only ever call the SoC specific probe function from
svs_platform_probe. No need to carry that function in a global
datastructure around.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Link: https://lore.kernel.org/r/20230111074528.29354-9-roger.lu@mediatek.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>