arm: mm: Set dma_ops_setup only for IOMMU_DOMAIN_DMA

Commit ef027fed ("arm: dma-mapping: don't attach the clients
to smmu device by default") changed the behavior such that
iommu clients need to attach manually, except for the
case of IOMMU_DOMAIN_DMA. There is a similar requirement for
detach, so modify dma_ops_setup accordingly.

Change-Id: I41117215e14552abbc621433eef16a44a33cd386
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>