pdch.cpp: Fix wrong annoying log line about non-scheduled ResourceReq received

It's perfectly fine receiving a Resource Request message under some
circumstances (as stated in the comment added in the commit).

To print issues only under non-expected circumstances, the function
rcv_resource_request need to be refactored:
* Destroying older UL_TBF is delayed because it is needed further
  down.
* When the old UL_TBF is FINISHED, it's an acceptable time to receive a
  Resource request, so we check if that's the case and don't print a
  warning in that case.

Change-Id: I4b4367126d6a16055cd2f45afc4a6b9c15a7c980
diff --git a/tests/tbf/TbfTest.err b/tests/tbf/TbfTest.err
index 800d4f8..29c8eb3 100644
--- a/tests/tbf/TbfTest.err
+++ b/tests/tbf/TbfTest.err
@@ -7902,7 +7902,7 @@
 ------------------------- RX : Uplink Control Block -------------------------
 Creating MS object, TLLI = 0x00000000
 MS requests UL TBF in packet resource request of single block, so we provide one:
-MS requests UL TBF in packet resource request of single block, but there is no resource request scheduled!
+(no TBF) MS requests UL TBF in PACKET RESOURCE REQ of single block, but there is no resource request scheduled!
 Modifying MS object, TLLI = 0x00000000, MS class 0 -> 11
 Modifying MS object, TLLI = 0x00000000, EGPRS MS class 0 -> 11
 ********** UL-TBF starts here **********