Update wrong references to bsc in sgsn code

Change-Id: I93f0dc721c2eff8a87fb9248882f24768f708713
diff --git a/src/gprs/gb_proxy_patch.c b/src/gprs/gb_proxy_patch.c
index 9cca9a8..251bb67 100644
--- a/src/gprs/gb_proxy_patch.c
+++ b/src/gprs/gb_proxy_patch.c
@@ -29,7 +29,7 @@
 #include <osmocom/core/rate_ctr.h>
 #include <osmocom/gsm/apn.h>
 
-extern void *tall_bsc_ctx;
+extern void *tall_sgsn_ctx;
 
 /* patch RA identifier in place */
 static void gbproxy_patch_raid(struct gsm48_ra_id *raid_enc, struct gbproxy_peer *peer,
@@ -420,7 +420,7 @@
 
 	if (rc == 0) {
 		match->enable = 1;
-		match->re_str = talloc_strdup(tall_bsc_ctx, filter);
+		match->re_str = talloc_strdup(tall_sgsn_ctx, filter);
 		return 0;
 	}