Reset the DSI hardware is needed to prevent different settings between
the bootloader and the kernel.

While here, also remove the undocumented and also not used
'mediatek,syscon-dsi' property.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210930103105.v4.5.I933f1532d7a1b2910843a9644c86a7d94a4b44e1@changeidSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>