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/vhost_user/handler.rs

@@ -9,7 +9,6 @@
 
 use super::super::{Queue, VirtioInterruptType};
 use super::{Error, Result};
-use epoll;
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::VirtioInterrupt;