fix syntax error in header file

[mknj]

quantum/keymap_extras/keymap_turkish_f.h won't compile without this fix.

Description

the one character change is really self explanatory

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

• [X ] My code follows the code style of this project: C, Python
• [ X] 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.
• [ X] I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• [ X] I have tested the changes and verified that they work and don't break anything (as well as I can manage).