accela: simplify, don't filter empty updates

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
accela: remove nonsense non-zero minimum

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
accela ui: rename deadzone to deadband

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
remove redundant mutex acquisition

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>