rust: doctest: use vertical import style

Convert `use` imports to vertical layout for better readability and
maintainability.

Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
Acked-by: David Gow <david@davidgow.net>
Link: https://patch.msgid.link/20260521-miscdev-use-format-v3-7-56240ca70d0c@linux.dev
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

scripts/rustdoc_test_gen.rs

@@ -31,8 +31,15 @@
 use std::{
     fs,
     fs::File,
-    io::{BufWriter, Read, Write},
-    path::{Path, PathBuf},
+    io::{
+        BufWriter,
+        Read,
+        Write, //
+    },
+    path::{
+        Path,
+        PathBuf, //
+    }, //
 };
 
 /// Find the real path to the original file based on the `file` portion of the test name.