main: Allow the use of let ahead and immediate return

On aarch64 there is no modification of the app struct however
refactoring to remove this would be very intrusive.

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

src/main.rs

@@ -125,6 +125,7 @@ fn prepare_default_values() -> (String, String, String) {
 }
 
 fn create_app(default_vcpus: String, default_memory: String, default_rng: String) -> Command {
+    #[allow(clippy::let_and_return)]
     let app = Command::new("cloud-hypervisor")
         // 'BUILT_VERSION' is set by the build script 'build.rs' at
         // compile time