GPRS_Components: add RA definition for single block packet access

Change-Id: I8997121f1b1207d4236f5911befc3c29278f37d8
diff --git a/pcu/PCU_Tests.ttcn b/pcu/PCU_Tests.ttcn
index 8facde7..dffbc4d 100644
--- a/pcu/PCU_Tests.ttcn
+++ b/pcu/PCU_Tests.ttcn
@@ -1132,8 +1132,8 @@
 	var uint32_t unused_fn;
 	var GprsMS ms;
 
-	/* 0111 0xxx: Single block packet access; one block period on a PDCH is needed for two phase packet access or other RR signalling purpose. */
-	var uint16_t ra := oct2int('70'O);
+	/* Single block (two phase) packet access */
+	var uint16_t ra := bit2int(chan_req_sb);
 	if (g_force_two_phase_access) {
 		/* If 2phase access is enforced by the network, then let's
 		   request a One phase packet access, we'll receive a single block