crypto: omap-des - handle NULL cipher request

If no data is provided for DES request, just return immediately. No
processing is needed in this case.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-des.c

@@ -637,6 +637,9 @@ static int omap_des_crypt(struct skcipher_request *req, unsigned long mode)
 		 !!(mode & FLAGS_ENCRYPT),
 		 !!(mode & FLAGS_CBC));
 
+	if (!req->cryptlen)
+		return 0;
+
 	if (!IS_ALIGNED(req->cryptlen, DES_BLOCK_SIZE))
 		return -EINVAL;