Input: ili210x - define and use chip operations structure

Instead of doing if/else if/else on the chip's model number let's define
chip operations structure and use it to perform indirect calls. With number
of protocols supported by the driver growing, this makes it better
maintainable.

This change includes fixes to checks whether the driver should continue
polling the controller by Sven Van Asbroeck <[email protected]>.

Tested-by: Adam Ford <[email protected]> #imx6q-logicpd
Tested-by: Sven Van Asbroeck <[email protected]> # ILI2118A variant
Signed-off-by: Dmitry Torokhov <[email protected]>

Author: dtor