UBI: fix error return code

Set the return variable to an error code as done elsewhere in the function.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}

// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Richard Weinberger <richard@nod.at>
diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
index 33bb1f2..6f27d9a 100644
--- a/drivers/mtd/ubi/attach.c
+++ b/drivers/mtd/ubi/attach.c
@@ -1453,8 +1453,10 @@
 		struct ubi_attach_info *scan_ai;
 
 		scan_ai = alloc_ai("ubi_ckh_aeb_slab_cache");
-		if (!scan_ai)
+		if (!scan_ai) {
+			err = -ENOMEM;
 			goto out_wl;
+		}
 
 		err = scan_all(ubi, scan_ai, 0);
 		if (err) {