drbd: Removed an unnecessary #undef

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_receiver.c

@@ -2963,7 +2963,6 @@ static int receive_sizes(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 		}
 		put_ldev(mdev);
 	}
-#undef min_not_zero
 
 	ddsf = be16_to_cpu(p->dds_flags);
 	if (get_ldev(mdev)) {