Document EBADF on string dumps

[gonX]

EBADF happens on Linux when trying to open a file descriptor (like a USB device) that can't be opened and running ioctl's on it:

Relevant code:
https://github.com/InfinityGhost/HIDSharpCore/blob/944a386ea6d51480ccd7dde7bb78e78768da8e1d/HidSharp/Platform/Linux/LinuxHidDevice.cs#L185-L195

Could probably also be fixed inside of OpenTabletDriver GUI by not trying to send string requests to knowingly unavailable devices?