CMemoryCardDriver: Correct erroneous fallthrough within HandleCardError()

In the game executable itself, there exists no fallthrough here (which
makes sense, given all IO errors would be reported as character set
errors, otherwise).

Runtime/MP1/CMemoryCardDriver.cpp

@@ -709,7 +709,7 @@ void CMemoryCardDriver::HandleCardError(ECardResult result, EState state) {
   case ECardResult::IOERROR:
     x10_state = state;
     x14_error = EError::CardIOError;
-    [[fallthrough]];
+    break;
   case ECardResult::ENCODING:
     x10_state = state;
     x14_error = EError::CardWrongCharacterSet;