crypto: mediatek - Fix wrong return value in mtk_desc_ring_alloc()

In case of memory allocation failure, a negative error code should
be returned.

Fixes: 785e5c616c849 ("crypto: mediatek - Add crypto driver support for some MediaTek chips")
Cc: Ryder Lee <[e-mail]>
Signed-off-by: Tianjia Zhang <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/mediatek/mtk-platform.c

···
 static int mtk_desc_ring_alloc(struct mtk_cryp *cryp)
 {
 	struct mtk_ring **ring = cryp->ring;
-	int i, err = ENOMEM;
+	int i;
 
 	for (i = 0; i < MTK_RING_MAX; i++) {
 		ring[i] = kzalloc(sizeof(**ring), GFP_KERNEL);
···
 				  ring[i]->cmd_base, ring[i]->cmd_dma);
 		kfree(ring[i]);
 	}
-	return err;
+	return -ENOMEM;
 }
 
 static int mtk_crypto_probe(struct platform_device *pdev)