ARM: S5P: Fix missed IRQ_EINT_BIT()

When merged patches, missed IRQ_EINT_BIT() definition from commit ea31fd43
(ARM: S5PV210: Add Power Management Support). The IRQ_EINT_BIT() is used
in the Power Management operation (plat-samsung/pm.c).

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>