tbf: Pass the MS object around instead of old_tbf

Currently the old TBF (either uplink or downlink) is passed around at
TBF allocation mainly to get information about the MS. To implement
more complex allocation algorithms, the MS object itself will be
needed anyway.

This commit replaces the old_tbf arguments by MS object arguments.

Sponsored-by: On-Waves ehf
diff --git a/src/tbf.h b/src/tbf.h
index 0f53a27..cf8cdfc 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -240,16 +240,15 @@
 
 struct gprs_rlcmac_ul_tbf *tbf_alloc_ul(struct gprs_rlcmac_bts *bts,
 	int8_t use_trx, uint8_t ms_class,
-	uint32_t tlli, uint8_t ta, struct gprs_rlcmac_tbf *dl_tbf);
+	uint32_t tlli, uint8_t ta, GprsMs *ms);
 
 struct gprs_rlcmac_ul_tbf *tbf_alloc_ul_tbf(struct gprs_rlcmac_bts *bts,
-	struct gprs_rlcmac_tbf *old_tbf,
+	GprsMs *ms,
 	uint8_t tfi, uint8_t trx,
 	uint8_t ms_class, uint8_t single_slot);
 
 struct gprs_rlcmac_dl_tbf *tbf_alloc_dl_tbf(struct gprs_rlcmac_bts *bts,
-	struct gprs_rlcmac_tbf *old_tbf,
-	uint8_t tfi, uint8_t trx,
+	GprsMs *ms, uint8_t tfi, uint8_t trx,
 	uint8_t ms_class, uint8_t single_slot);
 
 void tbf_free(struct gprs_rlcmac_tbf *tbf);