HID: bpf: add in-tree HID-BPF fix for the Huion Kamvas Pro 19

This tablets gets a lot of things wrong:
- the secondary button is reported through Secondary Tip Switch
- the third button is reported through Invert

Fortunately, before entering eraser mode, (so Invert = 1),
the tablet always sends an out-of-proximity event.
So we can detect that single event and:
- if there was none but the invert bit was toggled: this is the
  third button
- if there was this out-of-proximity event, we are entering
  eraser mode, and we will until the next out-of-proximity.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Peter Hutterer <[email protected]>
Signed-off-by: Benjamin Tissoires <[email protected]>

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