splhi -> disable_irqsave()

According to the old sources.

Basically, when pushing the packet back up via etheriq(), we want IRQs
off.  We're basically faking a packet arrival.
Slight improvement to NOW and seconds()

No need to serialize when dealing with msec and sec.
PCI cleanup

Not perfect, but it gets some of the muck out of the drivers.
Helper for registering device IRQs

This puts all the dirty hacks into one place, without drivers needing to
know about the particulars of IRQ routing, which interrupt handler table
to use, etc.
NIC drivers (esp the 9ns) uses register_dev_irq()

Also, devether is much nicer now, since it registers the IRQs for all
devices (instead of each doing their own), and it does so after having
fully set up the card (meaning, card->reset() returned).