fix keyboard fn keycodes not registering

This fixes some keyboard scancodes not registering keyup events
properly.
Combos like Fn+Right+Left, release Fn, release Left, Release right
would not send the correct keycode sequence to the host
Ported from
FrameworkComputer/ec@6288137

Signed-off-by: Kieran Levin <ktl@frame.work>

Author: kiram9