Input: edt-ft5x06 - make distinction between m06/m09/generic more clear

Since the driver also is useful for some non-EDT touchscreens based on
the focaltec chips introduce the concept of a "generic" focaltec based
touch.

Use a better heuristics for model detection and be more specific in the
source.

Signed-off-by: Simon Budig <simon.budig@kernelconcepts.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>