ucc_geth: add support for netpoll

This patch adds netpoll support for the QE UCC Gigabit Ethernet
driver. Tested using netconsole and KGDBoE.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>