pxa168: close race between napi and irq activation

In pxa168_eth_open() the irqs are enabled before napi. This opens a tiny time
window in which the irq handler is processed, disables irqs but then is not able
to schedule the not yet activated napi, leaving irqs disabled forever (since
irqs are reenabled in napi poll function).
Fix this race by activating napi before irqs are activated.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>