libceph: fix osdmap timestamp assignment

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 71603ac..94f068d 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -765,7 +765,7 @@
 	}
 
 	map->epoch++;
-	map->modified = map->modified;
+	map->modified = modified;
 	if (newcrush) {
 		if (map->crush)
 			crush_destroy(map->crush);