The interrupt control mechanism on Phantom cards has changed
substantially since the driver was initially written. This updates
the code to match the mechanism used in production firmware.
This is sufficient to allow DOS wget to function successfully using
the 3Com UNDI/NDIS, Intel UNDI/NDIS, and UNDIPD.COM UNDI/PD stacks.
Signed-off-by: Michael Brown <mcb30@etherboot.org>