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 <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

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

···
 			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++) {