Grant Tinker, who presided over NBC's spectacular rise from No. 3 to No. 1 among the commercial television networks, has been voted this year's Governors Award by the Academy of Television Arts & Sciences. Tinker, who stepped down as NBC chairman last year to found GTG Entertainment--a co-venture with the Gannett newspaper chain--will receive the award during the 39th annual prime-time Emmy Awards show Sept. 20. Tinker organized MTM Enterprises in 1970 and oversaw the production of such hit series as "The Mary Tyler Moore Show," "The Bob Newhart Show," "Lou Grant," "St. Elsewhere" and "Hill Street Blues."