dt-bindings: arm: mediatek: Merge MT8186 Voltorb entries

dt-bindings: arm: mediatek: Merge MT8186 Voltorb entries

There are only two different SKUs of Voltorb, and the only difference
between them is whether a touchscreen is present or not. This can be
detected by a simple I2C transfer to the address, instead of having
separate compatible strings and device trees.

Drop the SKU-specific compatible strings and just keep the generic
"google,voltorb" one.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20250617082004.1653492-3-wenst@chromium.org
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>