Input: ili210x - add resolution to chip operations structure

Optionally allow the touch screen resolution to be set by adding
it to the chip operations structure. If it is omitted (left zero),
the resolution defaults to 64K. Which is the previously hard-coded
value.

Set the ili2117 resolution to 2048, as indicated in its datasheet.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Link: https://lore.kernel.org/r/20191112210148.3535-1-TheSven73@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>