Drivers that use dma_virt_ops were meant to be rejected when testing
compatibility for P2PDMA.

This check got inadvertently dropped in one of the later versions of the
original patchset, so add it back.

Fixes: 52916982 ("PCI/P2PDMA: Support peer-to-peer memory")
Link: https://lore.kernel.org/r/20190702173544.21950-1-logang@deltatee.comSigned-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>