extract timezone from time sync answer and add to UTC timestamp

include/timesync.h

@@ -7,7 +7,7 @@
 #include "timekeeper.h"
 
 //#define TIME_SYNC_TRIGGER 100 // threshold for time sync [milliseconds]
-#define TIME_SYNC_FRAME_LENGTH 0x05 // timeserver answer frame length [bytes]
+#define TIME_SYNC_FRAME_LENGTH 0x07 // timeserver answer frame length [bytes]
 #define TIME_SYNC_FIXUP 4 // calibration to fixup processing time [milliseconds]
 
 void timesync_init(void);
@@ -16,4 +16,4 @@ int recv_timesync_ans(const uint8_t seq_no, const uint8_t buf[], const uint8_t b
 void process_timesync_req(void *taskparameter);
 void store_time_sync_req(uint32_t t_millisec);
 
-#endif
+#endif