misc: Remove redundant "use" imports

With the nightly toolchain (2024-02-18) cargo check will flag up
redundant imports either because they are pulled in by the prelude on
earlier match.

Remove those redundant imports.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

virtio-devices/src/vhost_user/net.rs

@@ -16,7 +16,6 @@ use std::result;
 use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Barrier, Mutex};
 use std::thread;
-use std::vec::Vec;
 use versionize::{VersionMap, Versionize, VersionizeResult};
 use versionize_derive::Versionize;
 use vhost::vhost_user::message::{VhostUserProtocolFeatures, VhostUserVirtioFeatures};