arm64: Fix the build error with "with-serde" feature

Signed-off-by: Michael Zhao <[email protected]>

Author: michael2012z

src/arm64/mod.rs

@@ -1,6 +1,9 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+#[cfg(feature = "with-serde")]
+use serde_derive::{Deserialize, Serialize};
+
 // Export 4.14 bindings when the feature kvm-v4_20_0 is not specified.
 #[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
 #[allow(clippy::all)]