myri10ge: check for DMA mapping errors

[ Upstream commit 10545937e866ccdbb7ab583031dbdcc6b14e4eb4 ]

On IOMMU systems DMA mapping can fail, we need to check for
that possibility.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>