Claude review: driver core: platform: tests: add test cases for correct swnode removal

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

Patch Review

**Good test coverage.** Three test cases cover the key scenarios:

1. **`platform_device_swnode_add_twice`**: Verifies a software node can be reused after device unregister (the original bug). Uses a bare `fwnode_init(&fwnode, NULL)` as the primary fwnode with the swnode as secondary.

2. **`platform_device_swnode_as_primary`**: Verifies a software node passed as primary fwnode survives device removal (testing the `fwnode_handle_get()` from patch 4). Checks with `software_node_fwnode()` that the node is still registered after unregister.

3. **`platform_device_two_swnodes`**: Verifies all three invalid dual-swnode combinations return `-EINVAL`.

One observation: the tests use `KUNIT_ASSERT_*` throughout rather than `KUNIT_EXPECT_*`. This means early assertions abort the test, preventing potential resource leaks from partial test execution. This is reasonable given the test structure, though it does mean later checks in a function are never reached if an early one fails.

**Verdict**: Good coverage for the changes being made.

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Generated by Claude Code Patch Reviewer