bts/tbf: Move the lists into the BTS and do the look-up from the BTS

The list belongs to the BTS. This makes cleaning this up more easy
and establishes a hierachy of resources that start from the BTS. The
debug_diagram code is now broken.
diff --git a/src/poll_controller.cpp b/src/poll_controller.cpp
index 461b1a2..115a68f 100644
--- a/src/poll_controller.cpp
+++ b/src/poll_controller.cpp
@@ -21,6 +21,7 @@
  */
 
 #include <poll_controller.h>
+#include <bts.h>
 #include <tbf.h>
 
 PollController::PollController(BTS& bts)
@@ -35,7 +36,7 @@
 	uint32_t elapsed;
 
 	/* check for poll timeout */
-	llist_for_each_entry(tbf, &gprs_rlcmac_ul_tbfs, list) {
+	llist_for_each_entry(tbf, &bts->ul_tbfs, list) {
 		if (tbf->poll_state == GPRS_RLCMAC_POLL_SCHED) {
 			elapsed = (frame_number + 2715648 - tbf->poll_fn)
 								% 2715648;
@@ -43,7 +44,7 @@
 				gprs_rlcmac_poll_timeout(bts, tbf);
 		}
 	}
-	llist_for_each_entry(tbf, &gprs_rlcmac_dl_tbfs, list) {
+	llist_for_each_entry(tbf, &bts->dl_tbfs, list) {
 		if (tbf->poll_state == GPRS_RLCMAC_POLL_SCHED) {
 			elapsed = (frame_number + 2715648 - tbf->poll_fn)
 								% 2715648;