ARM: SAMSUNG: if detected device tree skip irq init for S5P

It prevents from executing things already handled by pinctrl-exynos
driver, when device tree is available.

Signed-off-by: Mateusz Krawczuk <m.krawczuk@partner.samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>