ntb_tool: pass correct struct device to dma_alloc_coherent

Currently, ntb->dev is passed to dma_alloc_coherent
and dma_free_coherent calls. The returned dma_addr_t
is the CPU physical address. This works fine as long
as IOMMU is disabled. But when IOMMU is enabled, we
need to make sure that IOVA is returned for dma_addr_t.
So the correct way to achieve this is by changing the
first parameter of dma_alloc_coherent() as ntb->pdev->dev
instead.

Fixes: 5648e56d ("NTB: ntb_perf: Add full multi-port NTB API support")
Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>