Add new PDCH UL Controller, drop SBAllocator class

Right now we handle different types of UL allocations in different
classes like PollAllocator and SBAllocator, and they usually don't take
into account the other one in most cases. Furthermore, those objects are
usually per-BTS object, instead of per PDCH object.

This is a first step towards having a unified per-PDCH controller which
takes care of controlling what is scheduled and hence expected on the
uplink. Each PDCH has a UL Controller which keeps track of all reserved
uplink frame, be it SB, RRBP poll or USF assigned, all under the same
API.

As a first step, only the SBA part is fully implemented and used (being
it the easiest part to replace); TBF poll+usf will come in follow-up
patches later on. As a result, the SBAllocator per-BTS class dissappears
but some of its code is refactored/reused to provide more features to the
gprs_rlcmac_sba object, which is also further integrated into the new UL
Controller.

Related: OS#5020
Change-Id: I84b24beea4a1aa2c1528f41435f77bd16df2b947
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 970387d..f28c46f 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -285,7 +285,11 @@
 int pcu_rx_data_ind_pdtch(struct gprs_rlcmac_bts *bts, struct gprs_rlcmac_pdch *pdch, uint8_t *data,
 	uint8_t len, uint32_t fn, struct pcu_l1_meas *meas)
 {
-	return pdch->rcv_block(data, len, fn, meas);
+	int rc;
+
+	rc = pdch->rcv_block(data, len, fn, meas);
+	pdch_ulc_expire_fn(pdch->ulc, fn);
+	return rc;
 }
 
 static int pcu_rx_data_ind_bcch(struct gprs_rlcmac_bts *bts, uint8_t *data, uint8_t len)