dm raid: use DM_ENDIO_INCOMPLETE

Use a defined macro DM_ENDIO_INCOMPLETE instead of a numeric constant.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-raid1.c

@@ -1257,7 +1257,7 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio,
 			mempool_free(read_record, ms->read_record_pool);
 			map_context->ptr = NULL;
 			queue_bio(ms, bio, rw);
-			return 1;
+			return DM_ENDIO_INCOMPLETE;
 		}
 		DMERR("All replicated volumes dead, failing I/O");
 	}