Move gprs_rlcmac_ul_tbf::window to correct file

It wasn't move when all the UL specific code was moved to a separate
file.

Change-Id: I6f8c2d568ffdea3826ec1e11358d24eea6c9335b

src/tbf.cpp

@@ -1516,11 +1516,6 @@ bool gprs_rlcmac_tbf::is_control_ts(uint8_t ts) const
 	return ts == control_ts;
 }
 
-gprs_rlc_ul_window *gprs_rlcmac_ul_tbf::window()
-{
-	return &m_window;
-}
-
 struct gprs_rlcmac_ul_tbf *handle_tbf_reject(struct gprs_rlcmac_bts *bts,
 			GprsMs *ms, uint32_t tlli, uint8_t trx_no, uint8_t ts)
 {

src/tbf_ul.cpp

@@ -614,3 +614,8 @@ void gprs_rlcmac_ul_tbf::set_window_size()
 		  ws, b->ws_base, pcu_bitcount(ul_slots()), b->ws_pdch);
 	m_window.set_ws(ws);
 }
+
+gprs_rlc_ul_window *gprs_rlcmac_ul_tbf::window()
+{
+	return &m_window;
+}