omap3: pm: Add T2 Keypad as a wakeup source

Changes for setting the padconf value for sys_nirq line which is
connected to T2 INTR1. This will fix the T2 keypad wakeup.

Signed-off-by: Lesly A M <x0080970@ti.com>
Signed-off-by: Teerth Reddy <teerth@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>