misc: Further improve imports styling

By introducing `imports_granularity="Module"` format strategy,
effectively groups imports from the same module into one line or block,
improving maintainability and readability.

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

devices/src/legacy/cmos.rs

@@ -5,10 +5,9 @@
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
 use std::cmp::min;
-use std::mem;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Barrier};
-use std::thread;
+use std::{mem, thread};
 
 // https://github.com/rust-lang/libc/issues/1848
 #[cfg_attr(target_env = "musl", allow(deprecated))]

devices/src/legacy/gpio_pl061.rs

@@ -7,9 +7,8 @@
 //! This module implements an ARM PrimeCell General Purpose Input/Output(PL061) to support gracefully poweroff microvm from external.
 //!
 
-use std::io;
-use std::result;
 use std::sync::{Arc, Barrier};
+use std::{io, result};
 
 use serde::{Deserialize, Serialize};
 use thiserror::Error;

devices/src/legacy/i8042.rs

@@ -4,10 +4,8 @@
 //
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
-use std::sync::{
-    atomic::{AtomicBool, Ordering},
-    Arc, Barrier,
-};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, Barrier};
 use std::thread;
 
 use vm_device::BusDevice;