PCI/P2PDMA: dma_map() requests that traverse the host bridge

PCI/P2PDMA: dma_map() requests that traverse the host bridge

Any requests that traverse the host bridge will need to be mapped into the
IOMMU, so call dma_map_sg() inside pci_p2pdma_map_sg() when appropriate.

Similarly, call dma_unmap_sg() inside pci_p2pdma_unmap_sg().

Link: https://lore.kernel.org/r/20190730163545.4915-13-logang@deltatee.com
Link: https://lore.kernel.org/r/20190812173048.9186-13-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>