Input: ili210x - add missing negation for touch indication on ili210x

This adds the negation needed for proper finger detection on Ilitek
ili2107/ili210x. This fixes polling issues (on Amazon Kindle Fire)
caused by returning false for the cooresponding finger on the touchscreen.

Signed-off-by: Hansem Ro <hansemro@outlook.com>
Fixes: e3559442

 ("ili210x - rework the touchscreen sample processing")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>