ARM: dts: Enable PMIC interrupts for exynos4412-odroid-common

The ODROID kernel shows that the PMIC interrupt line is hooked up
to pin GPX3-2.

This is needed for the max77686-irq driver to create the PMIC IRQ
domain, which is needed by max77686-rtc.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Tested-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>