drbd: remove call to memset before free device/resource/connection

This revert c2258ffc ("drbd: poison free'd device, resource and
connection structs"), add memset is odd here for debugging, there are
some methods to accurately show what happened, such as kdump.
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lore.kernel.org/r/20221124015817.2729789-2-bobo.shaobowang@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -2217,7 +2217,6 @@ void drbd_destroy_device(struct kref *kref)
 		kref_put(&peer_device->connection->kref, drbd_destroy_connection);
 		kfree(peer_device);
 	}
-	memset(device, 0xfd, sizeof(*device));
 	kfree(device);
 	kref_put(&resource->kref, drbd_destroy_resource);
 }
@@ -2309,7 +2308,6 @@ void drbd_destroy_resource(struct kref *kref)
 	idr_destroy(&resource->devices);
 	free_cpumask_var(resource->cpu_mask);
 	kfree(resource->name);
-	memset(resource, 0xf2, sizeof(*resource));
 	kfree(resource);
 }
 
@@ -2650,7 +2648,6 @@ void drbd_destroy_connection(struct kref *kref)
 	drbd_free_socket(&connection->data);
 	kfree(connection->int_dig_in);
 	kfree(connection->int_dig_vv);
-	memset(connection, 0xfc, sizeof(*connection));
 	kfree(connection);
 	kref_put(&resource->kref, drbd_destroy_resource);
 }