templates: osmo-mgw.cfg.tmpl: address deprecation warnings

This commit fixes the following deprecation warnings:

range must end at an odd port number, autocorrecting port (16000) to: 16001
% Deprecated 'sdp audio-payload number <0-255>' config no longer has any effect
% Deprecated 'sdp audio-payload name NAME' config no longer has any effect

Change-Id: I98549abf8dd726fcc67a1de6a5f8bee64558883d
diff --git a/src/osmo_gsm_tester/templates/osmo-mgw.cfg.tmpl b/src/osmo_gsm_tester/templates/osmo-mgw.cfg.tmpl
index 5f351a4..ffdf9d3 100644
--- a/src/osmo_gsm_tester/templates/osmo-mgw.cfg.tmpl
+++ b/src/osmo_gsm_tester/templates/osmo-mgw.cfg.tmpl
@@ -7,10 +7,8 @@
 mgcp
  bind ip ${mgw.ip_address.addr}
  bind port 2427
- rtp net-range 4002 16000
+ rtp net-range 4002 16001
  rtp force-ptime 20
- sdp audio payload number 98
- sdp audio payload name AMR/8000
  number endpoints 31
  rtcp-omit
  rtp-accept-all 1