If IOVA allocation or IOMMU mapping fails, dma_free_wc() is invoked with
size=0 because of a typo, that triggers "kernel BUG at mm/vmalloc.c:124!".
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Reviewed-by: NMikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>