Claude review: soc: qcom: ubwc: Add Shikra UBWC config

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

Patch Review

```diff
+	{ .compatible = "qcom,shikra", .data = &qcm2290_data, },
```

Clean one-liner. The entry is correctly placed alphabetically (between `qcom,sdm845` and `qcom,sm4250`). Mapping to `qcm2290_data` is correct — this struct is defined as:

```c
static const struct qcom_ubwc_cfg_data qcm2290_data = {
	/* no UBWC */
	.highest_bank_bit = 15,
};
```

Since Shikra shares the same hardware as QCM2290, using the same UBWC config (which essentially disables UBWC but sets the correct `highest_bank_bit`) is the right choice. This also addresses the v1 feedback where `no_ubwc_data` was used incorrectly.

**Minor:** The commit message is missing a period at the end of "...for the UBWC settings". Trivial.

No functional issues.

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### Additional notes on the cover letter

1. **Duplicate Subject prefix:** The cover letter subject reads `"Subject: [PATCH v2 0/3] Subject: [PATCH 0/3] Add Shikra..."` — the nested `Subject:` should be removed.

2. **Stale diffstat:** The first diffstat in the cover letter (lines after the shortlog) lists `drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 1 +` and counts "5 files changed" while listing 6 files. This is a leftover from v1. The second diffstat (at the bottom) is correct. The stale one should be cleaned up in a v3 if one is needed.

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