The only user of this driver in mainline does not make use of the module
parameters, so let's remove them. All properties for this driver should be
set through DT or pdata.

Use touchscreen_parse_properties() to automatically set some of the common
touchscreen properties and derive the axis inversion through that.

And finally, use touchscreen_report_pos() to handle the DT properties
automatically instead of doing the inversion ourselves.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>