Tokyo stocks eked out small gains Friday with banks bought on higher interest rates while concerns over political uncertainty weighed on the market ahead of a general election in Japan. The 225-issue Nikkei Stock Average ended up 70.56 points, or 0.18 percent, from Thursday at 38,981.75. The broader Topix index finished 1.15 points, or 0.04 percent, higher at 2,688.98. On the top-tier Prime Market, gainers were led by pharmaceutical, machinery and bank issues. The U.S. dollar topped the 150 yen line overnight but weakened to the upper 149 yen range in Tokyo on yen buying after Japan’s top curr…