Already drm_iommu_attach_device and drm_iommu_detach_device check
whether support iommu internally, so we don't have to call
is_drm_iommu_supported before call them.
Signed-off-by: NJoonyoung Shim <jy0922.shim@samsung.com>
Tested-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NInki Dae <inki.dae@samsung.com>