By Scott Murdoch HONG KONG (Reuters) – Credit Suisse’s top two executives have told staff the bank is working to establish a stronger franchise in the longer term, according to a memo seen by Reuters on Saturday, amid uncertainty over a global review of its operations. The memo sent by Chairman Axel Lehmann and Chief Executive Ulrich Koerner said a “heightened level of media and market speculation” regarding the review had raised questions among the bank’s staff and clients. Reuters reported on Thursday that Credit Suisse had sounded out investors about a possible capital raising as it attempt…