net: ep93xx_eth: pass struct device to DMA API functions

We shouldn't use NULL for any DMA API functions, unless we are dealing with
ISA or EISA device. So pass correct struct dev pointer to these functions.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>