libceph: trivial fix for the incorrect debug output

This is a trivial fix for the debug output, as it is inconsistent
with the function name so may confuse people when debugging.

[elder@inktank.com: switched to use __func__]
Signed-off-by: NJiaju Zhang <jjzhang@suse.de>
Reviewed-by: NAlex Elder <elder@inktank.com>

net/ceph/osd_client.c

@@ -688,7 +688,7 @@ static void __remove_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
 
 static void remove_all_osds(struct ceph_osd_client *osdc)
 {
-	dout("__remove_old_osds %p\n", osdc);
+	dout("%s %p\n", __func__, osdc);
 	mutex_lock(&osdc->request_mutex);
 	while (!RB_EMPTY_ROOT(&osdc->osds)) {
 		struct ceph_osd *osd = rb_entry(rb_first(&osdc->osds),