Rename as_{dl,ul}_tbf -> tbf_as_{dl,ul}_tbf

Prefix the function accordingly to specify the input object.

Change-Id: I225568fe2cb5236817cdd9609354c24c66723606
diff --git a/src/gprs_ms.c b/src/gprs_ms.c
index df1c9be..0ccedb3 100644
--- a/src/gprs_ms.c
+++ b/src/gprs_ms.c
@@ -344,9 +344,9 @@
 void ms_attach_tbf(struct GprsMs *ms, struct gprs_rlcmac_tbf *tbf)
 {
 	if (tbf_direction(tbf) == GPRS_RLCMAC_DL_TBF)
-		ms_attach_dl_tbf(ms, as_dl_tbf(tbf));
+		ms_attach_dl_tbf(ms, tbf_as_dl_tbf(tbf));
 	else
-		ms_attach_ul_tbf(ms, as_ul_tbf(tbf));
+		ms_attach_ul_tbf(ms, tbf_as_ul_tbf(tbf));
 }
 
 void ms_detach_tbf(struct GprsMs *ms, struct gprs_rlcmac_tbf *tbf)