serial/pci_16550: make sure that interrupts are disabled during init

[szafonimateusz-mi]

Summary

• serial/pci_16550: make sure that interrupts are disabled during init
  Make sure that interrups are disabled during initialization.
  This is a proper fix for an unexpected MSI interrupt for PCI serial driver.

Impact

Testing

intel64 hw

[lupyuen]

[Experimental Bot, please feedback here]

This Pull Request appears to partially meet the NuttX requirements. Here's a breakdown:

Strengths:

• Summary: You've provided a concise explanation of the change's purpose and the specific code affected.
• Testing: You've included testing information, which is crucial.

Areas for Improvement:

• Impact: The "Impact" section is completely empty. You need to assess and describe the potential consequences of your changes across all listed categories. For example:
  • Is a new feature added? No, this seems like a bug fix.
  • Impact on user? Likely no, as this appears to be an internal driver fix.
  • Impact on build? Potentially no, unless your changes modify build scripts or configurations.
  • Impact on hardware? Possibly yes. This fix targets the PCI serial driver, so specify which architectures and boards are affected.
  • Impact on documentation, security, compatibility: Address each of these, even if the answer is "NO." Explain briefly why there's no impact.
• Testing:
  • While you mention "intel64 hw," be more specific about the target board and configuration.
  • The "Testing logs" sections are empty. Provide actual log snippets demonstrating the issue before your change and the improved behavior after.

Example for "Impact" Section:

## Impact

* Is new feature added? NO
* Is existing feature changed? YES, the PCI serial driver initialization now explicitly disables interrupts to prevent spurious MSI interrupts.
* Impact on user? NO. This is an internal driver fix and shouldn't affect user experience.
* Impact on build? NO. The changes are isolated to the driver code and do not modify the build system.
* Impact on hardware? YES. This fix applies to systems using the PCI 16550 serial driver, specifically on intel64 architectures. 
* Impact on documentation?  NO. The fix itself doesn't introduce new functionality or concepts requiring documentation updates.
* Impact on security?  Potentially YES. Unhandled interrupts could lead to unpredictable behavior, including security vulnerabilities. This fix mitigates such a risk. 
* Impact on compatibility? NO. The change aims to fix existing behavior and should not introduce compatibility issues.
* Anything else to consider?  N/A

Recommendations:

1. Complete the "Impact" section thoroughly. Carefully consider each point and explain your reasoning.
2. Populate the "Testing logs" sections. Include relevant log excerpts that clearly illustrate the problem and the solution.
3. Review the NuttX contribution guidelines: Ensure your PR adheres to any additional style or formatting requirements.

By providing a comprehensive and well-documented PR, you increase the chances of your contribution being reviewed and merged quickly.