Input: atmel_mxt_ts - add missing compatible strings to OF device table

Commit af503716 ("i2c: core: report OF style module alias for devices
registered via OF") fixed how the I2C core reports the module alias when
devices are registered via OF.

But the atmel_mxt_ts driver only has an "atmel,maxtouch" compatible in its
OF device ID table, so if a Device Tree is using a different one, autoload
won't be working for the module (the matching works because the I2C device
ID table is used as a fallback).

So add compatible strings for each of the entries in the I2C device table.

Fixes: af503716

 ("i2c: core: report OF style module alias for devices registered via OF")
Reported-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
[dtor: document which compatibles are deprecated and should not be used]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>