virtio: Describe virtio coherency in DT

We use cacheable accesses on our end of the virtio ring, so make sure
the guest is aware of that, and thus doesn't try to use non-cacheable
DMA buffers, by including the dma-coherent property on its DT node.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: do the same for the PCI node for virtio-pci devices]
Signed-off-by: Will Deacon <will.deacon@arm.com>
2 files changed