forcedeth msi bugfix

pci_enable_msi() replaces the INTx irq number in pci_dev->irq with the
new MSI irq number.
The forcedeth driver did not update the copy in netdevice->irq and
parts of the driver used the stale copy.
See bugzilla.kernel.org, bug 9047.

The patch
- updates netdevice->irq
- replaces all accesses to netdevice->irq with pci_dev->irq.

The patch is against 2.6.23.1. IMHO suitable for both 2.6.23 and 2.6.24

Signed-Off-By: Manfred Spraul <manfred@colorfullife.com>

Signed-off-by: Jeff Garzik <jeff@garzik.org>