async_core: fix formatting of use statement

Change-Id: I609da3eb581349315d1fb84a6a5fba233ec26b5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2048218
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Commit-Queue: Dylan Reid <dgreid@chromium.org>
Tested-by: Dylan Reid <dgreid@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/async_core/src/eventfd.rs b/async_core/src/eventfd.rs
index 4030fb8..b930f07 100644
--- a/async_core/src/eventfd.rs
+++ b/async_core/src/eventfd.rs
@@ -5,7 +5,7 @@
 use futures::Stream;
 use std::convert::TryFrom;
 use std::fmt::{self, Display};
-use std::os::unix::io::{AsRawFd};
+use std::os::unix::io::AsRawFd;
 use std::pin::Pin;
 use std::task::{Context, Poll};