library: fix t_RLCMAC_DlMacH: RRBP is always present

This template is not (yet) used anywhere, but let's fix it
anyway to avoid possible confusion.

Change-Id: Ic819f2b0eb292170de73abc7e200d79fcf02a76c
Signed-off-by: Vadim Yanitskiy <axilirator@gmail.com>
diff --git a/library/RLCMAC_Templates.ttcn b/library/RLCMAC_Templates.ttcn
index bcd2b23..f2945eb 100644
--- a/library/RLCMAC_Templates.ttcn
+++ b/library/RLCMAC_Templates.ttcn
@@ -356,11 +356,13 @@
 		}
 	}
 
-	template DlMacHeader t_RLCMAC_DlMacH(template MacPayloadType pt, template MacRrbp rrbp, template
-uint3_t usf) := {
+	template DlMacHeader t_RLCMAC_DlMacH(template (present) MacPayloadType pt,
+					     template (present) boolean rrbp_valid,
+					     template (present) MacRrbp rrbp,
+					     template (present) uint3_t usf) := {
 		payload_type := pt,
 		rrbp := rrbp,
-		rrbp_valid := ispresent(rrbp),
+		rrbp_valid := rrbp_valid,
 		usf := usf
 	}