Added set time callback with optional offset for BACnet TimeSynchronization services (#691)

ports/bsd/datetime-init.c

@@ -15,9 +15,24 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <time.h>
+#include "bacnet/basic/service/h_ts.h"
 #include "bacport.h"
 #include "bacnet/datetime.h"
 
+
+/**
+ * @brief Set offset from the system clock.
+ * @param bdate BACnet Date structure to hold local time
+ * @param btime BACnet Time structure to hold local time
+ * @param utc - True for UTC sync, False for Local time
+ * @return True if time is set
+ */
+void datetime_timesync(
+    BACNET_DATE *bdate, BACNET_TIME *btime, bool utc)
+{
+    return;
+}
+
 /**
  * @brief Get the date, time, timezone, and UTC offset from system
  * @param utc_time - the BACnet Date and Time structure to hold UTC time