drbd: Removed an unnecessary #undef

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index f4aba9f..f8cd3f2 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2963,7 +2963,6 @@
 		}
 		put_ldev(mdev);
 	}
-#undef min_not_zero
 
 	ddsf = be16_to_cpu(p->dds_flags);
 	if (get_ldev(mdev)) {