timeval: Make time_init() static and remove calls to it.

Since the timeval module now initializes itself on-demand, there is no
longer any need to initialize it explicitly, or to provide an interface to
do so.

utilities/ovs-dpctl.c

@@ -53,7 +53,6 @@ int
 main(int argc, char *argv[])
 {
     set_program_name(argv[0]);
-    time_init();
     vlog_init();
     parse_options(argc, argv);
     signal(SIGPIPE, SIG_IGN);