domain: init db connection in all processes

If the db_mode says we should cache the dialog table and only reload it
in MI proceeses, the module would not initialize the db connection for
SIP workers/timers. This would prevent the mi_script from running the
mi() commands.
This fix initializes the db connection in all proceses, thus enabling
the reload behavior from any process.

modules/domain/domain_mod.c

@@ -250,7 +250,7 @@ static int mod_init(void)
 static int child_init(int rank)
 {
 	/* Check if database is needed by worker processes only */
-	if ( db_mode==0 && (rank>=1) ) {
+	if (rank >= 1) {
 		if (domain_db_init(&db_url)<0) {
 			LM_ERR("Unable to connect to the database\n");
 			return -1;