arch: Remove serde usage

With the only struct using it now using Versionize then the serde
dependency can be removed.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

arch/src/aarch64/gic/gicv3.rs

@@ -60,7 +60,7 @@ pub mod kvm {
         vcpu_count: u64,
     }
 
-    #[derive(Serialize, Deserialize, Versionize)]
+    #[derive(Versionize)]
     pub struct Gicv3State {
         dist: Vec<u32>,
         rdist: Vec<u32>,

arch/src/lib.rs

@@ -10,9 +10,6 @@
 
 #[macro_use]
 extern crate log;
-#[cfg(target_arch = "aarch64")]
-#[macro_use]
-extern crate serde_derive;
 
 use std::fmt;
 use std::result;