Input: atmel_mxt_ts - make CHG line high after enabling interrupts

Make the CHG line (interrupt line) go high after the interrupts have been
enabled to make sure we don't miss the falling edge.

Signed-off-by: Iiro Valkonen <iiro.valkonen@atmel.com>
Acked-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>