EMERGING MARKETS-Latam stocks fall after 'fiscal cliff' setback

* U.S. budget talks falter after House vote * Commodities shares weigh on Brazil, Mexico bourses * Brazil Bovespa drops 1.29 pct, Mexico IPC down 0.48 pct By Asher Levine SAO PAULO, Dec 21 (Reuters) - Latin American stocks fell the most in over a month on Friday, as a new setback in U.S. budget negotiations weighed on risk appetite and investors sold off commodities shares following recent gains. The MSCI Latin American stock index fell 1.38 percent to 3,772.03, its first l