build: Address issues found by 1.43.0 clippy

These are mostly due to use of "bare use" statements and unnecessary vector
creation.

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

vm-virtio/src/net.rs

@@ -16,7 +16,6 @@ use super::{
 };
 use crate::VirtioInterrupt;
 use anyhow::anyhow;
-use epoll;
 use libc::EAGAIN;
 use libc::EFD_NONBLOCK;
 use net_util::{MacAddr, Tap};