net: add Xilinx ll_temac device driver

net: add Xilinx ll_temac device driver

This patch adds support for the Xilinx ll_temac 10/100/1000 Ethernet
device.  The ll_temac ipcore is typically used on Xilinx Virtex and
Spartan designs attached to either a PowerPC 4xx or Microblaze
processor.

At the present moment, this driver only works with Virtex5 PowerPC
designs because it assumes DCR is used to access the DMA registers.
However, the low level access to DMA registers is abstracted and
it should be easy to adapt for the other implementations.

I'm posting this driver now as an RFC.  There are still some things that
need to be tightened up, but it does appear to be stable.

Derived from driver code written by Yoshio Kashiwagi and David H. Lynch Jr.

Tested on Xilinx ML507 eval board with Base System Builder generated
FPGA design.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>