drivers/block/drbd/drbd_main.c: fix error path

Failure to create drbd_ee_mempool appears not to get checked.  Looks like
a copy-and-paste problem to me.
Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/block/drbd/drbd_main.c

@@ -2982,7 +2982,7 @@ static int drbd_create_mempools(void)
 
 	drbd_ee_mempool = mempool_create(number,
 		mempool_alloc_slab, mempool_free_slab, drbd_ee_cache);
-	if (drbd_request_mempool == NULL)
+	if (drbd_ee_mempool == NULL)
 		goto Enomem;
 
 	/* drbd's page pool */