gpio/samsung: fix GPIO interrupt registration for EXYNOS4 SoCs

Commit 1b39d5f2 introduced new common gpio driver for all Samsung GPIO
SoCs. The new driver doesn't correctly register GPIO interrupts on
Samsung Exynos4 SoCs. This is caused by a typo in define name. This
patch fixes this issue.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>