Input: remove duplicate ft6236 driver

The new(ish) ft6236 simply re-implements the M09 protocol of the
(much) older edt-ft5x06.c driver.

This commit removes this duplicate driver and adds the i2c ids and
dt compatible string to the edt-ft5x06.c driver to keep compatibility.

This commit also adds the standard touchscreen properties as optional
properties to the edt,ft5x06 binding, these were documented in the
focaltech,ft6236 bindingi, but were missing from the edt,ft5x06 doc.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>