ZURICH (Reuters) -Credit Suisse said on Thursday it will boost capital reserves after taking a multi-billion dollar hit from the collapse of U.S. investment fund Archegos, while regulators announced an enforcement case against the bank over the matter. Switzerland's second-biggest bank after UBS posted a slightly smaller-than-flagged 757 million Swiss franc ($825.97 million) first-quarter pre-tax loss, as the Archegos hit wiped out gains from a bumper trading quarter.