Nikkei edges up but investors still bewitched by Greece
* Market wants to wait until Greece's referendum - traders * China market moves focused - traders * Shio**gi soars after Credit Suisse's rating hike By Ayai Tomisawa TOKYO, June 30 (Reuters) - Japan's Nikkei share average edged up on Tuesday after posting its second-biggest daily drop this year, but the market remained concerned after a collapse in Greek bailout talks intensified fears that the country could exit the euro zone. The Nikkei share average rose 0.2 percent to 2