Braille: Fix typing quickly

On finishing releasing Braille keys, we should clear the just-commited
pattern, to reset the state to initial state, and avoid having to wait for
0.3s before typing the next pattern.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Jean-Philippe Mengual <jpmengual@hypra.fr>