chore: run cargo fmt

Due to style checks temporarily not running in CI between rust-vmm-ci
commits 752ad1322af8a5f632812b1b208b18bdf4e10ce6 and
92034f0e360567002db3f548ccc955bf0721dcf2, we did not catch a formatting
mistake in 33459e8.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

src/configurator/aarch64/fdt.rs

@@ -106,7 +106,7 @@ mod tests {
     }
 
     #[derive(Clone, Copy, Default)]
-    #[allow(dead_code)]  // rustc thinks the field is never read, but it is via `ByteValued` impl
+    #[allow(dead_code)] // rustc thinks the field is never read, but it is via `ByteValued` impl
     struct FdtPlaceholder([u8; FDT_MAX_SIZE]);
     unsafe impl ByteValued for FdtPlaceholder {}