libosmo-mgcp: cleanup audio codex alloc

No need to complicate audio codes with pointers, our "usual" string is
barely larger than a poointer, five times smaller than a talloc header,
and most importantly not really optional anyway...

Change-Id: Icc41643050a5e1ca3c66f307d60b6911ba1b8032
diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index eabaf53..077ac96 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -439,7 +439,7 @@
 	for (i = 0; i < codecs_used; i++) {
 		LOGPC(DLMGCP, LOGL_NOTICE, "%d=%s",
 		      rtp->codecs[i].payload_type,
-		      rtp->codecs[i].subtype_name ? rtp-> codecs[i].subtype_name : "unknown");
+		      strlen(rtp->codecs[i].subtype_name) ? rtp->codecs[i].subtype_name : "unknown");
 		LOGPC(DLMGCP, LOGL_NOTICE, " ");
 	}
 	LOGPC(DLMGCP, LOGL_NOTICE, "\n");