Clarify Error Message for PWM Support

[beyazkemal]

Hello,
I’ve been using the this library and recently encountered an issue related to PWM functionality. The current error message “pwm is not supported via sysfs” can be misleading for users, implying that PWM support is present but not through sysfs, whereas in reality, PWM functionality has not been implemented yet.

host/sysfs/gpio.go

Line 307 in 522a3cb

return p.wrap(errors.New("pwm is not supported via sysfs"))

I suggest revising this error message to something like “PWM functionality not implemented within the periph library” to provide clearer guidance to users encountering this issue. This adjustment would help prevent confusion and better inform users about the current status of PWM support within the library.

Thank you for considering this suggestion. I appreciate your efforts in maintaining and improving the library.

Best regards.