tbf, ...: Make the fields in the dl/ul struct member variables

There is no need for the union/struct anymore. Make the variable members
of the UL/DL class.

As a result gprs_rlc_dl_window gets a reset() method because
memset(&dir.dl, 0, sizeof(dir.dl)) doesn't work anymore in reuse_tbf().

Ticket: SYS#389
Sponsored by: On-Waves ehf
diff --git a/tests/alloc/AllocTest.cpp b/tests/alloc/AllocTest.cpp
index e89ff34..d711ad8 100644
--- a/tests/alloc/AllocTest.cpp
+++ b/tests/alloc/AllocTest.cpp
@@ -200,7 +200,7 @@
 		ul_tbf = tbf_alloc_ul_tbf(bts, dl_tbf, tfi, trx_no, ms_class, 0);
 		ul_tbf->m_tlli = 0x23;
 		ul_tbf->m_tlli_valid = true;
-		ul_tbf->dir.ul.contention_resolution_done = 1;
+		ul_tbf->m_contention_resolution_done = 1;
 		OSMO_ASSERT(ul_tbf);
 		dump_assignment(ul_tbf, "UL");
 
@@ -357,7 +357,7 @@
 		OSMO_ASSERT(ul_tbf);
 		ul_tbf->m_tlli = 0x23;
 		ul_tbf->m_tlli_valid = true;
-		ul_tbf->dir.ul.contention_resolution_done = 1;
+		ul_tbf->m_contention_resolution_done = 1;
 
 		OSMO_ASSERT(dl_tbf->first_common_ts == ul_tbf->first_common_ts);