crypto: x86/cast5-avx - fix ECB encryption when long sg follows short one

With ecb-cast5-avx, if a 128+ byte scatterlist element followed a
shorter one, then the algorithm accidentally encrypted/decrypted only 8
bytes instead of the expected 128 bytes.  Fix it by setting the
encryption/decryption 'fn' correctly.

Fixes: c12ab20b ("crypto: cast5/avx - avoid using temporary stack buffers")
Cc: <stable@vger.kernel.org> # v3.8+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/cast5_avx_glue.c

@@ -66,8 +66,6 @@ static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
 	void (*fn)(struct cast5_ctx *ctx, u8 *dst, const u8 *src);
 	int err;
 
-	fn = (enc) ? cast5_ecb_enc_16way : cast5_ecb_dec_16way;
-
 	err = blkcipher_walk_virt(desc, walk);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
@@ -79,6 +77,7 @@ static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
 
 		/* Process multi-block batch */
 		if (nbytes >= bsize * CAST5_PARALLEL_BLOCKS) {
+			fn = (enc) ? cast5_ecb_enc_16way : cast5_ecb_dec_16way;
 			do {
 				fn(ctx, wdst, wsrc);