Claude review: gpu: nova-core: gsp: fix stale doc comments on command queue methods

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

Patch Review

Clean documentation-only patch. Updates doc comments on `send_command` and `receive_msg` to match current behavior.

The change from `EAGAIN` to `ERANGE` in the doc comments for non-matching messages aligns with what appears to be an earlier refactoring:

```rust
+    /// - `ERANGE` if the message had a recognized but non-matching function code.
```

And the addition of the `EMSGSIZE` error documentation for `send_command`:
```rust
+    /// - `EMSGSIZE` if the command exceeds the maximum queue element size.
```

This is a good cleanup. Note that the existing tree's `send_command` doc mentions `EAGAIN` for insufficient space (line 487 of the current tree), while this patch's context shows `ETIMEDOUT` -- this implies the prerequisite series already changed the space-waiting behavior to use a polling timeout, which is consistent.

No issues.

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