I have the same 88E8056 and it works fine in 10.7.4. Make a legacy kext for it, I believe this still works:
Also there's this that you can use instead of EthernetBuiltIn=y
(read the whole thread first!)
Thanks for this Gringo. Read through it all, but before proceeding decided to reinstall the 10.7.3 to 10.7.4 update again. Lo and behold, ethernet is now working. Not sure why, but perhaps the original install hiccupped along the way. Anyway... all is good here now again, and my P5K-E system is back in full working order.