arm64: dts: mt8173-elm: Remove ddc property from panel

The elm and hana devices uses an Embedded DisplayPort (eDP) as interface
for its panel, so the DDC channel specified in the binding is useless.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Tested-by: Bilal Wasim <bilal.wasim@imgtec.com>
Link: https://lore.kernel.org/r/20200826090218.682931-1-enric.balletbo@collabora.com


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