Input: nomadik-ske-keypad - fix a loop timeout test

The loop exits with "timeout" set to -1 not to 0.

Fixes: 1158f0f1 ("Input: add support for Nomadik SKE keypad controller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>