drm/exynos: remove to use ifdef CONFIG_ARM_DMA_USE_IOMMU
drm/exynos: remove to use ifdef CONFIG_ARM_DMA_USE_IOMMU

If CONFIG_ARM_DMA_USE_IOMMU is disable, CONFIG_DRM_EXYNOS_IOMMU also is
disable. When CONFIG_DRM_EXYNOS_IOMMU is disable,
is_drm_iommu_supported() returns always false, so we can remove to use
ifdef CONFIG_ARM_DMA_USE_IOMMU in is_drm_iommu_supported().

Signed-off-by: Joonyoung Shim <b2207686f8c5343cf0f505ae1d5720ecb0c3202a@samsung.com>
Tested-by: Marek Szyprowski <2a0259761cc3e88db42be5300c1579a67c77e65e@samsung.com>
Signed-off-by: Inki Dae <bae4a7a27bbc965064e97edd6e179ac4979db440@samsung.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs