arm64: dma_mapping: Add support for .dma_mapping_error() ops

If dma_map_single() or dma_map_page() fail to create a mapping, clients
can check these errors by testing the returned address with
.dma_mapping_error(). The implementation was missing for DMA IOMMU
mapper.  Add it.

Change-Id: I7e62bdbcd013cab915134fce9e55b1e7b580915a
Signed-off-by: Neeti Desai <neetid@codeaurora.org>
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>