ortp: make sure the ortp scheduler is started

the function osmo_rtp_init() is initializing ortp at the start of the
application. However, it does not start the scheduler of ortp, which
leads into error log messages in some situatios.

- make sure that ortp_scheduler_init() is called with osmo_rtp_init()

Change-Id: I3a63c23f5ede47773b6a249a48ecebd5d3b45ace
Related: OS#3299
diff --git a/src/trau/osmo_ortp.c b/src/trau/osmo_ortp.c
index 8ea05e4..18a6123 100644
--- a/src/trau/osmo_ortp.c
+++ b/src/trau/osmo_ortp.c
@@ -290,6 +290,7 @@
 
 	ortp_set_log_handler(my_ortp_logfn);
 	create_payload_types();
+	ortp_scheduler_init();
 }
 
 /*! \brief Set Osmocom RTP socket parameters