media: rc: mce_kbd decoder: fix stuck keys

The MCE Remote sends a 0 scancode when keys are released. If this is not
received or decoded, then keys can get "stuck"; the keyup event is not
sent since the input_sync() is missing from the timeout handler.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>