net: fec: change data structure to support multiqueue

net: fec: change data structure to support multiqueue

This patch just change data structure to support multi-queue.
Only 1 queue enabled.

Ethernet multiqueue mechanism can improve performance in SMP system.
For single hw queue, multiqueue can balance cpu loading.
For multi hw queues, multiple cores can process network packets in parallel,
and refer the article for the detail advantage for multiqueue:
http://vger.kernel.org/~davem/davem_nyc09.pdf

Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Frank Li <frank.li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>