MGCP_Test: allow setting of fmtp parameters

When creating an RTP flow, there is currently no way to set SDP fmtp
parameters. Lets add a template and a parameter in order to be able to
set those parameters.

Change-Id: Ic1840d5023cb3888a17980f4ed08c19175864896
Related: SYS#4470
diff --git a/library/MGCP_Templates.ttcn b/library/MGCP_Templates.ttcn
index afdc33d..f720553 100644
--- a/library/MGCP_Templates.ttcn
+++ b/library/MGCP_Templates.ttcn
@@ -280,6 +280,11 @@
 			attr_value := int2str(p)
 		}
 	}
+	template SDP_attribute ts_SDP_fmtp(integer fmt, charstring val) := {
+		fmtp := {
+			attr_value := int2str(fmt) & " " & val
+		}
+	}
 
 	function f_mgcp_extract_par(MgcpMessage msg, MgcpInfoCode code) return charstring {
 		var MgcpParameterList pars;