arm64: dts: mediatek: asurada: Add I2C touchscreen

All machines of the Asurada platform have a touchscreen at address 0x10
in the I2C0 bus, but the devices vary: Spherion has the Elan eKTH3500
touchscreen, while Hayato has a generic HID-over-i2c touchscreen.

Add common support for the touchscreens on the platform and the
specifics in each board file.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20220629155956.1138955-12-nfraprado@collabora.com


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