aplay/aes67: Remove unused field

The sap hash is generated when the packet is created

src/audio/playback/aes67.cpp

@@ -78,7 +78,6 @@ struct Rtp_stream{
 struct Sap_session{
         uint64_t sess_id = 0; //Numeric session-id from RFC
         uint64_t sess_ver = 0;
-        uint16_t sap_hash = 0; //Hash of sap packet that contained sdp for this version of session
         std::string origin_address;
         std::string name;
         std::string description;