iommu/exynos: Properly release device from the default domain in ->remove

IOMMU core doesn't detach device from the default domain before calling
->iommu_remove_device, so check that and do the proper cleanup or
warn if device is still attached to non-default domain.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>