ARM: dts: exynos: Remove obsolete IRQ lines on Exynos3250

In commit 7222e8db ("iommu/exynos: Fix build errors") Exynos3250
IOMMU driver stopped supporting two IRQ lines. The second IRQ line in
DTS is ignored and is not needed.

Signed-off-by: Maciej Falkowski <m.falkowski@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>