ExternalKeyboard: Debounce the Connected/Disconnected events
ExternalKeyboard: Debounce the Connected/Disconnected events

Until we find a way to fine-tune the evdev device parsing, we'll often
have at least two devices per keyboard, but we only need a single event
;).

poire-z/koreader,koreader/koreader,koreader/koreader,poire-z/koreader,NiLuJe/koreader,NiLuJe/koreader