avformat/tls_openssl: do not cleanup tls after a successful dtls_start()

Regression since 8e11e2cdb82299e7f0b6d8884bf2bc65c1c3f5e8.

Signed-off-by: Marton Balint <cus@passwd.hu>
diff --git a/libavformat/tls_openssl.c b/libavformat/tls_openssl.c
index c2adaa3..c7d6ff6 100644
--- a/libavformat/tls_openssl.c
+++ b/libavformat/tls_openssl.c
@@ -834,7 +834,7 @@
 
     av_log(c, AV_LOG_VERBOSE, "Setup ok, MTU=%d\n", c->tls_shared.mtu);
 
-    ret = 0;
+    return 0;
 fail:
     tls_close(h);
     return ret;