Fix invalid read after list concatenation

g_slist_concat uses the items from second list directly so they should
not be freed.
diff --git a/attrib/gatt.c b/attrib/gatt.c
index f3b513e..20bb96f 100644
--- a/attrib/gatt.c
+++ b/attrib/gatt.c
@@ -121,7 +121,6 @@
 	dp->primaries = g_slist_concat(dp->primaries, ranges);
 
 	last = g_slist_last(ranges);
-	g_slist_free(ranges);
 	range = last->data;
 
 	if (range->end == 0xffff)