aoe: fix use after free in aoedev_by_aoeaddr()

We should return NULL on failure instead of returning a freed pointer.

Signed-off-by: Dan Carpenter <[e-mail]>
Cc: Ed Cashin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/block/aoe/aoedev.c

···
 	d->targets = kcalloc(NTARGETS, sizeof(*d->targets), GFP_ATOMIC);
 	if (!d->targets) {
 		kfree(d);
+		d = NULL;
 		goto out;
 	}
 	d->ntargets = NTARGETS;