library: s/tr_RLCMAC_DUMMY_CTRL/tr_RLCMAC_DL_DUMMY_CTRL/

There also exists UL equivalent of this message, for which I am
planning to add a template.  Let's clarify direction in the name.

Change-Id: I3b19c6679eb432b062e28aee9dd1220dbf33ee31
diff --git a/library/RLCMAC_Templates.ttcn b/library/RLCMAC_Templates.ttcn
index e398491..3b1e40a 100644
--- a/library/RLCMAC_Templates.ttcn
+++ b/library/RLCMAC_Templates.ttcn
@@ -529,7 +529,7 @@
 		}
 	}
 
-	template RlcmacDlBlock tr_RLCMAC_DUMMY_CTRL(template uint3_t usf := ?, template PageMode page_mode := ?) := {
+	template RlcmacDlBlock tr_RLCMAC_DL_DUMMY_CTRL(template uint3_t usf := ?, template PageMode page_mode := ?) := {
 		ctrl := {
 			mac_hdr := {
 				payload_type := (MAC_PT_RLCMAC_NO_OPT, MAC_PT_RLCMAC_OPT),