to poll succesfully even if we are sharing the interrupt.
Register the interrupt handler before the attach.
This commit makes the 294x PCI shared interrupt compliant. This has
been tested with an aic7870 motherboard controller and a 294x in the
same machine shareing an irq.
a device specific shutdown routine for devconf. Assign the value of this
to the kern_devconf struct. Implement a device shutdown routine for if_de
that disables the device. This will stop the device from corrupting memory
after a reboot.
