arm64: dts: mediatek: pumpkin: Remove input-name property

This property doesn't seem to exist in the documentation nor
in source code, but for some reason it is defined in a bunch
of device trees.

Signed-off-by: Dang Huynh <danct12@riseup.net>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/20220425064850.246228-1-danct12@riseup.net


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