Move tbf::free_all static methods to proper object files

Move each method to the object on which they operate, be it a trx or a
pdch ts.

Change-Id: Ida715cbf384431d37b2b192fbd7882957c93a4d1
diff --git a/src/pdch.h b/src/pdch.h
index 2413ef7..57e0f43 100644
--- a/src/pdch.h
+++ b/src/pdch.h
@@ -183,3 +183,11 @@
 }
 
 #endif /* __cplusplus */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+void pdch_free_all_tbf(struct gprs_rlcmac_pdch *pdch);
+#ifdef __cplusplus
+}
+#endif