ARM: S5P: add required chained_irq_enter/exit to gpio-int code

This patch adds chained IRQ enter/exit functions to gpio interrupt
handler in order to function correctly on primary controllers with
different methods of flow control.

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>