soc: mediatek: mtk-svs: keep svs alive if CONFIG_DEBUG_FS not supported

Some projects might not support CONFIG_DEBUG_FS but still needs svs to be
alive. Therefore, enclose debug cmd codes with CONFIG_DEBUG_FS to make sure
svs can be alive when CONFIG_DEBUG_FS not supported.

Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Link: https://lore.kernel.org/r/20230111074528.29354-8-roger.lu@mediatek.com


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