Claude review: block: rnull: use `LocalModule` for `THIS_MODULE`

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

Updates `drivers/block/rnull/configfs.rs` to replace:
```rust
use super::{
    NullBlkDevice,
    THIS_MODULE,
};
```
with:
```rust
use super::NullBlkDevice;
use crate::LocalModule;
```

**Observations:**

1. This is a straightforward mechanical update. The old `THIS_MODULE` import from the parent module is replaced by importing `LocalModule` from the crate root, which then gets used via the `configfs_attrs!` macro expansion (patched in patch 6).

2. The `LocalModule` import is needed because `configfs_attrs!` now refers to `LocalModule` by name.

**No issues found.**

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**Summary:** This is a clean, well-structured 7-patch series fixing a real use-after-free vulnerability in Rust kernel drivers. The design choice of threading `THIS_MODULE` through the type system via `ModuleMetadata` + `#[vtable]` auto-injection is sound and minimizes per-driver boilerplate. No correctness issues identified. The series is ready to merge pending the prerequisite patches it depends on.

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Generated by Claude Code Patch Reviewer