keyboard: Cancel keys on unmap

The shift key is supposed to capitalize the next letter, unless
it is set to latched on long press. This doesn't currently work,
as the level switch replaces the current layer of keys with a
new layer, so the release that is supposed to cancel the long
press happens on an unrelated key.

Fix this by resetting all state on unmap, including the long-press
timeout.
12 jobs for !2390 with unshift in 3 minutes and 2 seconds (queued for 33 seconds)
latest merge request