Convert the dma transfers to be dmaengine based, now pxa has a dmaengine
slave driver. This makes this driver a bit more PXA agnostic.

The driver was only compile tested. The risk is quite small as no
current PXA platform I'm aware of is using smc911x driver.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>