MT#60476 sdp_create: no need to initialze prtp to NULL

It will anyway always get set to NULL during each
media iteration.

Change-Id: I1994a1228df59a8f7d8f21a71c6612270815b24e

daemon/sdp.c

@@ -3707,7 +3707,7 @@ int sdp_create(str *out, struct call_monologue *monologue, sdp_ng_flags *flags)
 {
 	const char *err = NULL;
 	GString *s = NULL;
-	const struct transport_protocol *prtp = NULL;
+	const struct transport_protocol *prtp;
 	unsigned int port;
 
 	err = "Need at least one media";