Add NULL and DISC frame definitions

For some reason, the rather simple NULL and DISC frames as specified
in GSM/3GPP TS 04.64 were not yet part of this TITAN module.  Let's
change that.

Change-Id: I789e2afa1af03b73522af1f969b3c319245401f4
Signed-off-by: Harald Welte <laforge@gnumonks.org>
diff --git a/src/LLC_Types.ttcn b/src/LLC_Types.ttcn
index 22c888f..0e4922d 100644
--- a/src/LLC_Types.ttcn
+++ b/src/LLC_Types.ttcn
@@ -207,6 +207,10 @@
 
 type octetstring DM_Information length(0);
 
+type octetstring NULL_Information length(0);
+
+type octetstring DISC_Information length(0);
+
 type record FRMR_Information
 {
   RejectedFrameControlField   rejectedFrameControlField,
@@ -265,7 +269,9 @@
   SABM_Information      sABM,
   FRMR_Information      fRMR,
   DM_Information        dM,
-  XID_Information       xID
+  XID_Information       xID,
+  NULL_Information	nULL,
+  DISC_Information	dISC
 };
 
 
@@ -306,6 +312,8 @@
                                          fRMR, control_field.mBits = '1000'B;
                                            dM, control_field.mBits = '0001'B;
                                           xID, control_field.mBits = '1011'B;
+					 nULL, control_field.mBits = '0000'B;
+					 dISC, control_field.mBits = '0100'B;
                                           )";
 };