Fix DD warnings for RGBKB boards

[fauxpark]

Description

⚠ rgbkb/mun/rev1: RGB_MATRIX_MAXIMUM_BRIGHTNESS->rgb_matrix.max_brightness: invalid literal for int() with base 10: 'RGBLIGHT_LIMIT_VAL'
⚠ rgbkb/mun/rev1: RGB_MATRIX_SPLIT->rgb_matrix.split_count: invalid literal for int() with base 10: 'RGBLED_SPLIT'
⚠ rgbkb/sol/rev1: RGB_MATRIX_MAXIMUM_BRIGHTNESS->rgb_matrix.max_brightness: invalid literal for int() with base 10: 'RGBLIGHT_LIMIT_VAL'
⚠ rgbkb/sol/rev2: RGB_MATRIX_MAXIMUM_BRIGHTNESS->rgb_matrix.max_brightness: invalid literal for int() with base 10: 'RGBLIGHT_LIMIT_VAL'
⚠ rgbkb/sol3/rev1: RGB_MATRIX_MAXIMUM_BRIGHTNESS->rgb_matrix.max_brightness: invalid literal for int() with base 10: 'RGBLIGHT_LIMIT_VAL'
⚠ rgbkb/sol3/rev1: RGB_MATRIX_SPLIT->rgb_matrix.split_count: invalid literal for int() with base 10: 'RGBLED_SPLIT'

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).