Claude review: gpu: nova-core: gsp: add checking oversized commands

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

Patch Review

Adds the `EMSGSIZE` check before attempting allocation. The binding for `GSP_MSG_QUEUE_ELEMENT_SIZE_MAX` (65536 = 16 * 4096) is consistent with the 16-page limit mentioned in the cover letter.

The check:
```rust
if size_of::<GspMsgElement>() + size > GSP_MSG_QUEUE_ELEMENT_SIZE_MAX {
    return Err(EMSGSIZE);
}
```

This is correct - after patch 8 lands, this check becomes effectively dead code for the `allocate_command` path because `SplitState::new` will split commands before they reach `allocate_command` (renamed to `send_single_command`). However, keeping it as a defensive check in `allocate_command` is reasonable as it documents the invariant and catches programming errors.

Minor: the trailing `//` comment on the import line (line 1131 in the mbox) is a `rustfmt` artifact for forcing multi-line formatting. It's consistent with the codebase style.

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Generated by Claude Code Patch Reviewer