Update ucc_geth.c for new workqueue structure

The workqueue interface changed with David Howell's patch on 11/22/2006
(SHA 65f27f38446e1976cc98fd3004b110fedcddd189).  Several drivers were
updated with that patch to handle the new interface, but ucc_geth.c
was not one of them.  This patch updates ucc_geth.c to support the new
model.

A compiler warning in set_mac_addr() was also fixed.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>