crypto: atmel - only treat EBUSY as transient if backlog

The Atmel SHA driver was treating -EBUSY as indication of queueing
to backlog without checking that backlog is enabled for the request.

Fix it by checking request flags.

Cc: <stable@vger.kernel.org>
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/atmel-sha.c

@@ -1204,7 +1204,9 @@ static int atmel_sha_finup(struct ahash_request *req)
 	ctx->flags |= SHA_FLAGS_FINUP;
 
 	err1 = atmel_sha_update(req);
-	if (err1 == -EINPROGRESS || err1 == -EBUSY)
+	if (err1 == -EINPROGRESS ||
+	    (err1 == -EBUSY && (ahash_request_flags(req) &
+				CRYPTO_TFM_REQ_MAY_BACKLOG)))
 		return err1;
 
 	/*