arm64: dts: mediatek: mt6795-xperia-m5: Add Synaptics RMI4 Touchscreen

Add the RMI4 Touchscreen on I2C2 and its pin definitions.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230327083647.22017-14-angelogioacchino.delregno@collabora.com


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