[i2c] separate imports

We've typically separated imports in 3 categories:
- Rust standard library
- external crates
- project internal imports (such as imports from user defined modules)

Signed-off-by: Andreea Florescu <fandree@amazon.com>

src/i2c/src/i2c.rs

@@ -5,9 +5,10 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 
-use libc::{c_ulong, ioctl, EADDRINUSE, EADDRNOTAVAIL, EINVAL};
 use std::fs::{File, OpenOptions};
 use std::os::unix::io::AsRawFd;
+
+use libc::{c_ulong, ioctl, EADDRINUSE, EADDRNOTAVAIL, EINVAL};
 use vmm_sys_util::errno::{errno_result, Error, Result};
 
 // The type of the `req` parameter is different for the `musl` library. This will enable

src/i2c/src/main.rs

@@ -8,15 +8,19 @@
 mod i2c;
 mod vhu_i2c;
 
-use clap::{load_yaml, App, ArgMatches};
-use i2c::{I2cAdapter, I2cAdapterTrait, I2cMap};
 use std::sync::{Arc, RwLock};
 use std::thread::spawn;
+
+use clap::{load_yaml, App, ArgMatches};
 use vhost::{vhost_user, vhost_user::Listener};
 use vhost_user_backend::VhostUserDaemon;
-use vhu_i2c::VhostUserI2cBackend;
 use vm_memory::{GuestMemoryAtomic, GuestMemoryMmap};
 
+use i2c::{I2cAdapter, I2cAdapterTrait, I2cMap};
+use std::convert::TryFrom;
+use std::num::ParseIntError;
+use vhu_i2c::VhostUserI2cBackend;
+
 fn start_daemon<T: I2cAdapterTrait>(
     backend: Arc<RwLock<VhostUserI2cBackend<T>>>,
     listener: Listener,