Add the default in switch implementation to prevent gcc build error

[MarcChen46]

Description

When the KnobService.py generate the ConfigDataGenerated.h, it generated the ValidateEnumValueXXXX function that has a switch implementation, but it missed the default: in the switch implementation that cause gcc build failed with [-Werror=switch] error.

• Impacts functionality?
  • Functionality - Does the change ultimately impact how firmware functions?
  • Examples: Add a new library, publish a new PPI, update an algorithm, ...
• Impacts security?
  • Security - Does the change have a direct security impact on an application,
    flow, or firmware?
  • Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
• Breaking change?
  • Breaking change - Will anyone consuming this change experience a break
    in build or boot behavior?
  • Examples: Add a new library class, move a module to a different repo, call
    a function in a new library class in a pre-existing module, ...
• Includes tests?
  • Tests - Does the change include any explicit test code?
  • Examples: Unit tests, integration tests, robot tests, ...
• Includes documentation?
  • Documentation - Does the change contain explicit documentation additions
    outside direct code modifications (and comments)?
  • Examples: Update readme file, add feature readme file, link to documentation
    on an a separate Web page, ...

How This Was Tested

Verified the build that include ConfigDataGenerated.h by gcc compile

Integration Instructions

N/A

[codecov-commenter]

Codecov Report

Merging #263 (2bf0703) into main (04e6f18) will decrease coverage by 0.02%.
The diff coverage is 0.00%.

❗ Current head 2bf0703 differs from pull request most recent head c79fdeb. Consider uploading reports for the commit c79fdeb to get more accurate results

@@            Coverage Diff             @@
##             main     #263      +/-   ##
==========================================
- Coverage   27.40%   27.39%   -0.02%     
==========================================
  Files          16       16              
  Lines        4550     4552       +2     
==========================================
  Hits         1247     1247              
- Misses       3303     3305       +2     

Flag	Coverage Δ
Linux	27.39% <0.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
SetupDataPkg/Tools/KnobService.py	0.00% <0.00%> (ø)

[MarcChen46]

@apop5 @kuqin12, please help reviewing it, thanks.