cpu/cc430: do normal assignment instead of memcpy

cpu/cc430/periph/rtc.c

@@ -60,7 +60,7 @@ int rtc_set_time(struct tm *localt)
     }
 
     /* copy time to be set */
-    memcpy(&time_to_set, localt, sizeof(struct tm));
+    time_to_set = *localt;
     set_time = 1;
     return 0;
 }