The .map_sg() op now expects an error code instead of zero on failure.

Propagate the error up if vio_dma_iommu_map_sg() fails.

ppc_iommu_map_sg() may fail either because of iommu_range_alloc() or
because of tbl->it_ops->set(). The former only supports returning an
error with DMA_MAPPING_ERROR and an examination of the latter indicates
that it may return arch-specific errors (for example,
tce_buildmulti_pSeriesLP()). Hence, coalesce all of those errors into
-EIO, per the documentation on dma_map_sgtable().
Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Geoff Levand <geoff@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>