EGPRS: PUAN encoding: add test case to show wrong urbb_len issue

This patch adds a test case which expects a current bug with EGPRS PUAN
encoding when VQ != VR. The test's expectation is corrected along with
the bugfix in a subsequent commit

Adds test_tbf_puan_urbb_len to describe the following bug:
EGPRS PUAN encoding disregards the urbb_len, leading to identical PUAN
messages regardless of the urbb_len.

Related: OS#1793

Change-Id: I00662a564f64c0c83627401ae8f7bfef0f0a5de8
diff --git a/tests/tbf/TbfTest.ok b/tests/tbf/TbfTest.ok
index c38417d..dda72ef 100644
--- a/tests/tbf/TbfTest.ok
+++ b/tests/tbf/TbfTest.ok
@@ -60,3 +60,5 @@
 Testing retx for MCS 4 to reseg_mcs 1
 Testing retx for MCS 6 to reseg_mcs 3
 === end test_tbf_egprs_spb_dl ===
+=== start test_tbf_puan_urbb_len ===
+=== end test_tbf_puan_urbb_len ===