Fix joystick EV_KEY handling indexing below 0 on keyboard input

[Liam-Malone]

This fixes an issue I was running into where input from my keyboard running ZMK firmware would be handled as a joystick, and would index the associated keymap with a value less than 0 (code - BTN_MISC, where code was smaller than BTN_MISC).

This issue was causing SIGILL crashes on my laptop every time I used that particular keyboard within my programs using glfw.

[elmindreda]

Thank you for the bug report! It seems the core issue is that GLFW is treating a keyboard like a joystick in the first place?

[Liam-Malone]

Hi, yes the core issue is my keyboard being treated both as a keyboard and as a joystick.

[Liam-Malone]

I will note:
I only did the band-aid fix of preventing indexing below 0, my keyboard still registers as both gamepad and keyboard. This was enough of a fix to permit me to keep working on my own project, but doesn't resolve the core issue.

I have also since tested with another keyboard running QMK firmware and found NO issues with that keyboard. So I can say again that this issue is only occurring on the keyboard that has ZMK firmware, when connected to my laptop.