fix double free in osmo_gsup_client_enc_send()

Change-Id: Iee675fd498ab0867ac2411d9142358f513276182
diff --git a/src/gsupclient/gsup_client.c b/src/gsupclient/gsup_client.c
index c8408fd..814d5a2 100644
--- a/src/gsupclient/gsup_client.c
+++ b/src/gsupclient/gsup_client.c
@@ -386,7 +386,8 @@
 	rc = osmo_gsup_client_send(gsupc, gsup_msgb);
 	if (rc) {
 		LOGP(DLGSUP, LOGL_ERROR, "Couldn't send GSUP message\n");
-		goto error;
+		/* Do not free, osmo_gsup_client_send() already has. */
+		return rc;
 	}
 
 	return 0;