Fix Coverity warning about mixing enums

Coverity says:
>>>     CID 190310:  Incorrect expression  (MIXED_ENUMS)
>>>     Mixing enum types "CborType" and "QCborStreamReader::Type" for "type_".

Change-Id: Ifbadc62ac2d04a9a8952fffd1589e6e304fc7703
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/serialization/qcborstream.cpp

@@ -1934,7 +1934,7 @@ inline void QCborStreamReader::preparse()
             // for negative integer and we don't have separate types for Boolean,
             // Null and Undefined).
             if (type_ == CborBooleanType || type_ == CborNullType || type_ == CborUndefinedType) {
-                type_ = SimpleType;
+                type_ = CborSimpleType;
                 value64 = quint8(d->buffer.at(d->bufferStart)) - CborSimpleType;
             } else {
                 // Using internal TinyCBOR API!