Dec 12 (Reuters) - Britain's FTSE 100 index is seen opening up 13 points, on Tuesday, according to financial bookmakers. * SKY: Comcast Corp dropped its bid for most of the assets of Twenty-First Century Fox Inc, that includes a stake in European pay-TV provider Sky PLC, leaving Walt Disney Co as the sole suitor to acquire the assets. * HSBC: HSBC drew a line under its punishment for lapses in anti-money laundering controls on Monday, saying the U.S. Department of Justice (DoJ)