net: velocity: Convert to generic dma functions

Remove the pci_* dma functions and replace with the more generic
versions.

In preparation of adding platform support, a new struct device *dev
is added to struct velocity_info which can be used by both the pci
and platform code.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>