au1000_eth: use 'unsigned long' for irqflags

The patch was generated using the Coccinelle semantic patch framework.

Cc: Julia Lawall <julia@diku.dk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>