arm64: dts: mt8183: refine gamma compatible name

mt8183 gamma is different with mt8173
remove mt8173 compatible name for mt8183 gamma

Fixes: 91f9c963 ("arm64: dts: mt8183: Add display nodes for MT8183")
Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210128112314.1304160-3-hsinyi@chromium.org


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