PCU: move RAW_NS into own file to use it in the SGSN tests

In preparation to test the SGSN role of NS

Change-Id: Id91aa81c4fb6689cd1353d88b4806d26868769e8
diff --git a/pcu/PCU_Tests_SNS.ttcn b/pcu/PCU_Tests_SNS.ttcn
index fc98979..dd133a3 100644
--- a/pcu/PCU_Tests_SNS.ttcn
+++ b/pcu/PCU_Tests_SNS.ttcn
@@ -16,6 +16,7 @@
 import from Osmocom_Gb_Types all;
 import from NS_CodecPort all;
 import from NS_Types all;
+import from RAW_NS all;
 
 /**********************************************************************************
  * Modern Gb/IP bring-up test cases using IP Sub-Network Service (SNS)