Input: small tweak to autorepeat handling

If a device does not support autorepeat or does not emit any key events we
should not be scanning all events in a packet to decide if we should start
or stop autorepeat function.

Signed-off-by: Anshul Garg <anshul.g@samsung.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>