Input: omap-keypad - interrupt disable fix

The GPIO interrupts are disabled several times after the first key press.
No need to disable - again - the interrupts in the omap_kp_scan_keypad
function on OMAP2.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>