Fix mistake in ts_to_uint function

packet-exchange/src/utilities.c

@@ -7,7 +7,7 @@
 #include "utilities.h"
 
 uint64_t ts_to_uint(struct timespec t) {
-  return t.tv_nsec * NSEC_PER_SEC + t.tv_sec;
+  return t.tv_sec * NSEC_PER_SEC + t.tv_nsec;
 }
 
 void add_ns(struct timespec *t, uint64_t ns) {