Redo the interupt handling of sky2 driver based on the IRQ mangement
documentation. All interrupts are handled by the device0 NAPI poll
routine.

Don't need to adjust interrupt mask in IRQ context, done only when
changing device under RTNL. Therefore don't need hwlock anymore.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>