Move out tbf subclasses from tbf.h to their own headers

It's a good start towards clearing current mess between parent and the 2
children classes.

Change-Id: Ibc22ea2e02609af7ee058b8bc15df2115d4c6f60
diff --git a/tests/alloc/AllocTest.cpp b/tests/alloc/AllocTest.cpp
index 64d6a50..123f879 100644
--- a/tests/alloc/AllocTest.cpp
+++ b/tests/alloc/AllocTest.cpp
@@ -20,6 +20,7 @@
 #include "gprs_rlcmac.h"
 #include "gprs_debug.h"
 #include "tbf.h"
+#include "tbf_ul.h"
 #include "bts.h"
 
 #include <string.h>