* European shares surge on report ECB to buy corporate bonds* Wall Street to start up, earnings from Coca Cola, McDonalds due* Nikkei slips 2 pct, giving back half of Monday&aposs rally* US Treasury yields back above 2.20 pct as dollar reboundsBy Marc JonesLONDON, Oct 21 (Reuters) - European shares got a major lift while the euro and the region&aposs bond yields fell on Tuesday after European Cent