ocfs2: Proper cleanup in case of error in ocfs2_register_hb_callbacks()

If ocfs2_register_hb_callbacks() succeeds on its first callback but fails
its second, it doesn't release the first on the way out. Fix that.

While we're at it, o2hb_unregister_callback() never returns anything but
0, so let's make it void.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index 1718215..69caf3e 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -1638,17 +1638,8 @@
 
 void o2net_unregister_hb_callbacks(void)
 {
-	int ret;
-
-	ret = o2hb_unregister_callback(&o2net_hb_up);
-	if (ret < 0)
-		mlog(ML_ERROR, "Status return %d unregistering heartbeat up "
-		     "callback!\n", ret);
-
-	ret = o2hb_unregister_callback(&o2net_hb_down);
-	if (ret < 0)
-		mlog(ML_ERROR, "Status return %d unregistering heartbeat down "
-		     "callback!\n", ret);
+	o2hb_unregister_callback(&o2net_hb_up);
+	o2hb_unregister_callback(&o2net_hb_down);
 }
 
 int o2net_register_hb_callbacks(void)