Simplify TS alloc: don't use PDCH for free TFI

Don't use PDCH from free TFI lookup routine. This allows for simpler
function which can be moved to mslot_class.c alongside with other
similar helpers.

Change-Id: Ie154866900453d232a890f7b9a30911b451525a1
Related: OS#2282
diff --git a/src/gprs_rlcmac_ts_alloc.cpp b/src/gprs_rlcmac_ts_alloc.cpp
index 29e41f5..6791b03 100644
--- a/src/gprs_rlcmac_ts_alloc.cpp
+++ b/src/gprs_rlcmac_ts_alloc.cpp
@@ -62,23 +62,6 @@
 	return was_set;
 }
 
-static inline int8_t find_free_tfi(const struct gprs_rlcmac_pdch *pdch, enum gprs_rlcmac_tbf_direction dir)
-{
-	uint32_t tfi_map = pdch->assigned_tfi(dir);
-	int8_t tfi;
-
-	if (tfi_map == NO_FREE_TFI)
-		return -1;
-
-	/* look for USF, don't use USF=7 */
-	for (tfi = 0; tfi < 32; tfi++) {
-		if (!(tfi_map & (1 << tfi)))
-			return tfi;
-	}
-
-	return -1;
-}
-
 static int find_possible_pdchs(const struct gprs_rlcmac_trx *trx, size_t max_slots, uint8_t mask,
 			       const char *mask_reason = NULL)
 {
@@ -187,7 +170,7 @@
 			/* We have found a candidate */
 			/* Make sure that a TFI is available */
 			if (free_tfi) {
-				tfi = find_free_tfi(pdch, dir);
+				tfi = find_free_tfi(pdch->assigned_tfi(dir));
 				if (tfi < 0) {
 					LOGP(DRLCMAC, LOGL_DEBUG,
 						"- Skipping TS %d, because "