ARM: dts: tbs711: Fix touchscreen compatible

The edt,edt-ft5x06 compatible has never been a valid compatible
according to the binding. Let's change for one that is.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20210901091852.479202-46-maxime@cerno.tech