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>

virtio-devices/src/iommu.rs

@@ -3,13 +3,12 @@
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
 use std::collections::BTreeMap;
-use std::io;
 use std::mem::size_of;
 use std::ops::Bound::Included;
 use std::os::unix::io::AsRawFd;
-use std::result;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Barrier, Mutex, RwLock};
+use std::{io, result};
 
 use anyhow::anyhow;
 use seccompiler::SeccompAction;
@@ -25,15 +24,13 @@ use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottabl
 use vm_virtio::AccessPlatform;
 use vmm_sys_util::eventfd::EventFd;
 
-use super::Error as DeviceError;
 use super::{
-    ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, VirtioCommon, VirtioDevice,
-    VirtioDeviceType, EPOLL_HELPER_EVENT_LAST, VIRTIO_F_VERSION_1,
+    ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, Error as DeviceError,
+    VirtioCommon, VirtioDevice, VirtioDeviceType, EPOLL_HELPER_EVENT_LAST, VIRTIO_F_VERSION_1,
 };
 use crate::seccomp_filters::Thread;
 use crate::thread_helper::spawn_virtio_thread;
-use crate::GuestMemoryMmap;
-use crate::{DmaRemapping, VirtioInterrupt, VirtioInterruptType};
+use crate::{DmaRemapping, GuestMemoryMmap, VirtioInterrupt, VirtioInterruptType};
 
 /// Queues sizes
 const QUEUE_SIZE: u16 = 256;