Update tg4x.overlay

[shaggnanigans]

Board/Shield Check-list

• [ ] This board/shield is tested working on real hardware
• [ ] Definitions follow the general style of other shields/boards upstream (Reference)
• [ ] .zmk.yml metadata file added
• [ ] Proper Copyright + License headers added to applicable files (Generally, we stick to "The ZMK Contributors" for copyrights to help avoid churn when files get edited)
• [ ] General consistent formatting of DeviceTree files
• [ ] Keymaps do not use deprecated key defines (Check using the upgrader tool)
• [ ] &pro_micro used in favor of &pro_micro_d/a if applicable
• [ ] If split, no name added for the right/peripheral half
• [ ] Kconfig.defconfig file correctly wraps all configuration in conditional on the shield symbol
• [ ] .conf file has optional extra features commented out
• [ ] Keyboard/PCB is part of a shipped group buy or is generally available in stock to purchase (OSH/personal projects without general availability should create a zmk-config repo instead)

[caksoylar]

I assume this change is to accomodate for the smaller right shift layout, where the bottom row has 12 keys. The current README states it is for "2u right shift": https://github.com/zmkfirmware/zmk/tree/main/app/boards/shields/tg4x/#board-revision-and-layout-notes

The right way to handle this would be to define multiple matrix transforms, corresponding to the different physical layout options. Having said that, shield PRs seem to be on a bit of a hiatus; so you might want to just create a custom shield in your config repo with these changes.