added support for 1-line bus width sdmmc device mode

[pebri86]

This MR adds support for 1-line bus width mode in the SDMMC driver to accommodate boards with limited pin availability, while maintaining the 4-line mode as the default.

Summary by CodeRabbit

• New Features
  • SD/MMC device bus width is now configurable via configuration settings (default: 4-bit mode), replacing the previously fixed value.

[coderabbitai]

📝 Walkthrough

Walkthrough

The changes make the SDMMC device bus width configurable. Previously, the bus width was hard-coded to 4 bits. Now it is a configurable parameter in the Config structure with a default value of 4. The SdmmcDevice class stores this configuration in a private member variable and uses it when initializing the SDMMC slot configuration. This allows different bus width values to be set when creating an SdmmcDevice instance while maintaining backward compatibility through the default value.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: adding support for configurable SDMMC bus width (specifically 1-line mode), which directly corresponds to the code changes that make bus width dynamic instead of hard-coded.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[KenVanHoeylandt]

Thank you for improving the driver.
The code looks good to me, so I'll merge it after the automated builds have succeed.