Ethernet on x86_64 fc7t4

[Chuck Forsberg WA7KGX N2469R]

I replaced the 100 mbit ethernet card with a 
National Semiconductor Corporation DP83820 10/100/1000 Ethernet
Controller

This is a bit of overkill for a network connection that tops out
at less than 10 mbit but it does seem to eliminate the missing
transmit interrupts.

Given the random nature of the problem with the 100 mbit cards,
it will take some time to decide the problem is really
fixed.