Update RXDCTL and TXDCTL values to eliminate MPCs

Ultimately, these values should be auto-tuned based on performance, or at the very least, should be configurable. For now, these values are the same that are used in the e1000e driver so it's probably a safe starting point for us. This should close issue #35 as there are no more missed packet counts on my hardware or your hardware.

Luke, I'm not sure if you like or dislike me leaving the comments in the code. I just left them so you and others could see where the values came from. I can just as easily remove them if you'd like.

Sorry, I can't contribute as much as I'd love to, but even a little commit here and there still makes me feel like part of the party! Believe it or not, I'm still reading through the intel data sheet, my lua book, SDN in general, etc ... My day job will require working for the next two weekends solid (user conversions).