crypto: cavium/nitrox - Fix 'nitrox_get_first_device()' when ndevlist is fully iterated

When a list is completely iterated with 'list_for_each_entry(x, ...)', x is
not NULL at the end.

While at it, remove a useless initialization of the ndev variable. It
is overridden by 'list_for_each_entry'.

Fixes: f2663872 ("crypto: cavium - Register the CNN55XX supported crypto algorithms.")
Cc: <stable@vger.kernel.org>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/cavium/nitrox/nitrox_main.c

@@ -278,7 +278,7 @@ static void nitrox_remove_from_devlist(struct nitrox_device *ndev)
 
 struct nitrox_device *nitrox_get_first_device(void)
 {
-	struct nitrox_device *ndev = NULL;
+	struct nitrox_device *ndev;
 
 	mutex_lock(&devlist_lock);
 	list_for_each_entry(ndev, &ndevlist, list) {
@@ -286,7 +286,7 @@ struct nitrox_device *nitrox_get_first_device(void)
 			break;
 	}
 	mutex_unlock(&devlist_lock);
-	if (!ndev)
+	if (&ndev->list == &ndevlist)
 		return NULL;
 
 	refcount_inc(&ndev->refcnt);