Input: ili210x - do not unconditionally mark touchscreen as wakeup source

I2C devices that are supposed to be wakeup sources should be instantiated
with I2C_CLIENT_WAKE flag (which can be either set by in board info, or
retrieved from "wakeup-source" property); individual drivers should not be
marking devices as wakeup sources unconditionally.

Tested-by: Adam Ford <aford173@gmail.com> #imx6q-logicpd
Tested-by: Sven Van Asbroeck <TheSven73@gmail.com> # ILI2118A variant
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>