crypto: sunxi-ss - Fix a possible driver hang with ciphers

The sun4i_ss_opti_poll function cipher data until the output miter have
a length of 0.
If the crypto API client, give more SGs than necessary this could result
in an infinite loop.
Fix it by checking for remaining bytes, just like sun4i_ss_cipher_poll().
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/sunxi-ss/sun4i-ss-cipher.c

@@ -104,7 +104,7 @@ static int sun4i_ss_opti_poll(struct ablkcipher_request *areq)
 			sg_miter_next(&mo);
 			oo = 0;
 		}
-	} while (mo.length > 0);
+	} while (oleft > 0);
 
 	if (areq->info) {
 		for (i = 0; i < 4 && i < ivsize / 4; i++) {