AMI_Functions: Tx ActionID instead of ActionId

The AMI documentation webpage mentions "ActionId", but Asterisk is
always returning "ActionID" in all response messages.
Any of the 2 is parsed fine by Asterisk since the keys are case
insensitive, but anyway let's use same case as what Asterisk is actually
transmitting to make reading of output easier.

Change-Id: I8097e461fd0cadfa780d52ab1666e41b9d2b8a0e
diff --git a/asterisk/AMI_Functions.ttcn b/asterisk/AMI_Functions.ttcn
index c1211a9..3044c17 100644
--- a/asterisk/AMI_Functions.ttcn
+++ b/asterisk/AMI_Functions.ttcn
@@ -26,7 +26,7 @@
 }
 
 const charstring AMI_FIELD_ACTION := "Action";
-const charstring AMI_FIELD_ACTION_ID := "ActionId";
+const charstring AMI_FIELD_ACTION_ID := "ActionID";
 const charstring AMI_FIELD_USERNAME := "Username";
 const charstring AMI_FIELD_SECRET := "Secret";
 const charstring AMI_FIELD_RESPONSE := "Response";