gprs_ns2: implement BLOCK/UNBLOCK of a NSVC by vty

The vty should be able to block or unblock a specific NSVC.
Further more this case is special for the UNITDATA as those
can be still received until the other side response to the BLOCK PDU.

Related: OS#4939
Change-Id: Ic0ce3c5fabc8644cc1ee71a8f6dd783fadf7b84d
diff --git a/tests/gb/gprs_ns2_test.ok b/tests/gb/gprs_ns2_test.ok
index 62bbbfe..27c72fa 100644
--- a/tests/gb/gprs_ns2_test.ok
+++ b/tests/gb/gprs_ns2_test.ok
@@ -6,5 +6,10 @@
 ---- Test with NSVC[2]
 ---- Test with NSVC[1] removed
 --- Finish NSE transfer cap
+--- Testing NSE block unblock nsvc
+---- Create NSE + Binds
+---- Create NSVC[i]
+---- Create NSVC[i]
+--- Finish NSE block unblock nsvc
 ===== NS2 protocol test END