use osmo_fd_setup() whenever applicable

Change-Id: I1586e855d37670af2602fc26b5d1fc72a32d1929
diff --git a/src/libosmo-mgcp/mgcp_osmux.c b/src/libosmo-mgcp/mgcp_osmux.c
index 9a3c950..a7c0eef 100644
--- a/src/libosmo-mgcp/mgcp_osmux.c
+++ b/src/libosmo-mgcp/mgcp_osmux.c
@@ -416,8 +416,7 @@
 {
 	int ret;
 
-	osmux_fd.cb = osmux_read_fd_cb;
-	osmux_fd.data = cfg;
+	osmo_fd_setup(&osmux_fd, -1, OSMO_FD_READ, osmux_read_fd_cb, cfg, 0);
 
 	ret = mgcp_create_bind(cfg->osmux_addr, &osmux_fd, cfg->osmux_port);
 	if (ret < 0) {
@@ -426,7 +425,6 @@
 		return ret;
 	}
 	mgcp_set_ip_tos(osmux_fd.fd, cfg->endp_dscp);
-	osmux_fd.when |= OSMO_FD_READ;
 
 	ret = osmo_fd_register(&osmux_fd);
 	if (ret < 0) {