arm64: dts: mediatek: mt6779: Remove syscon compatible from pin controller

Remove syscon compatible string from pin controller to follow
DT bindings and pass checks. Adding the syscon compatible to
the DT bindings documentation instead causes a different check
error due to the syscon document specifying a maximum of 1 item
in the reg property, while this has 9. This pin controller has
never been, and will never be, used as a syscon, hence it is
safe to drop this compatible.

Signed-off-by: Yassine Oudjana <y.oudjana@protonmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221028153505.23741-2-y.oudjana@protonmail.com


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