AbstractPrefixCodeTranscoder::operator==(): fix compilation

```
/home/lebedevri/rawspeed/src/librawspeed/decompressors/../codes/AbstractPrefixCodeTranscoder.h:96:43: error: no member named 'codeValues' in 'AbstractPrefixCodeTranscoder<CodeTag>'
   96 |            code.Base::codeValues == other.codeValues;
      |                                     ~~~~~ ^

```

Author: LebedevRI

src/librawspeed/codes/AbstractPrefixCodeTranscoder.h

@@ -93,7 +93,7 @@ template <typename CodeTag> class AbstractPrefixCodeTranscoder {
 
   bool operator==(const AbstractPrefixCodeTranscoder& other) const {
     return code.symbols == other.code.symbols &&
-           code.Base::codeValues == other.codeValues;
+           code.Base::codeValues == other.code.Base::codeValues;
   }
 };