Input: ili210x - fetch touchscreen geometry from DT

Fetching the geometry from the ILI251x registers seems unreliable and
sometimes returns all zeroes. Add support for fetching the geometry and
axis inversion from DT instead.

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>