LOS ANGELES (Reuters) - Poor Jim Carrey. His movies have raked in nearly $2 billion at box offices, but now a leading entertainment magazine says the comedian's asking price of $25 million a film has become "a bit of a gamble." ADVERTISEMENT In its issue out this week, Entertainment Weekly rates top stars on whether they are worth the money. Among those whose asking prices have become too high are Carrey, Nicole Kidman, Will Ferrell and Eddie Murphy, the magazine said. It added that after years of ever-rising star salaries, the prices for top talent are now coming down because...