logging fixup: shorter names for LOGGING_FILTER_* and LOGGING_CTX_*

In libosmocore, my patch was merged to master a bit too soon. To accomodate the
request for naming that matches the general "LOG" prefix instead of "LOGGING",
a fixup was committed to libosmocore. Adjust for that.

Original patch: change-id I5c343630020f4b108099696fd96c2111614c8067
The fixup: change-id I424fe3f12ea620338902b2bb8230544bde3f1a93

Change-Id: Ib2ec5e4884aa90f48051ee2f832af557aa525991
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 58fdaa3..1cae832 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -159,7 +159,7 @@
 		     gsm_ts_and_pchan_name(lchan->ts), log_name, chan_nr);
 
 	if (lchan->conn)
-		log_set_context(LOGGING_CTX_VLR_SUBSCR, lchan->conn->subscr);
+		log_set_context(LOG_CTX_VLR_SUBSCR, lchan->conn->subscr);
 
 	return lchan;
 }