net/ethernet: ks8851_mll fix irq handling

There a two different irq variables ks->irq and netdev->irq.
Only ks->irq is set on probe, so disabling irq in ks_start_xmit fails.

This patches remove ks->irq from private data and use only netdev->irq.

Tested on a kernel 3.0 based OMAP4430 SMP Board

Signed-off-by: Jan Weitzel <j.weitzel@phytec.de>
Signed-off-by: David S. Miller <davem@davemloft.net>