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/src/gprs_rlcmac_ts_alloc.cpp b/src/gprs_rlcmac_ts_alloc.cpp
index 0476d6d..cf3f9a9 100644
--- a/src/gprs_rlcmac_ts_alloc.cpp
+++ b/src/gprs_rlcmac_ts_alloc.cpp
@@ -23,6 +23,7 @@
 #include <gprs_debug.h>
 #include <bts.h>
 #include <tbf.h>
+#include <tbf_ul.h>
 #include <pdch.h>
 #include <gprs_ms.h>
 #include <pcu_utils.h>