Claude review: drm: Suppress intentional warning backtraces in scaling unit tests

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

Patch Review

**Good real-world demonstration of the API.**

```c
+	int expected_warnings = IS_ENABLED(CONFIG_BUG) ?
+			(params->expected_scaling_factor == -EINVAL) : 0;
+	int scaling_factor = INT_MIN;
```

The `INT_MIN` initialization is defensive — if the `kunit_warning_suppress` block fails to set up (returns NULL due to allocation failure), `scaling_factor` retains a sentinel value that won't accidentally match the expected value. The `#include <linux/limits.h>` is added for `INT_MIN`.

The `expected_warnings` computation is clever: on `CONFIG_BUG=n`, WARN_ON is a no-op, so the counter stays zero. On `CONFIG_BUG=y`, warnings fire only for the `-EINVAL` test cases (bad parameters). The boolean-to-int conversion `(params->expected_scaling_factor == -EINVAL)` yields 0 or 1, which is correct.

```c
+	kunit_warning_suppress(test) {
+		scaling_factor = drm_rect_calc_hscale(&params->src, &params->dst,
+						      params->min_range,
+						      params->max_range);
+		KUNIT_EXPECT_SUPPRESSED_WARNING_COUNT(test, expected_warnings);
+	}
 
 	KUNIT_EXPECT_EQ(test, scaling_factor, params->expected_scaling_factor);
```

The `KUNIT_EXPECT_EQ` check on `scaling_factor` is correctly placed *outside* the suppress block — it doesn't need suppression and this keeps the suppress scope as narrow as possible. The warning count check is inside the block as required by the API.

**No issues found.**

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