media: rc: mce_kbd decoder: low timeout values cause double keydowns

The mce keyboard repeats pressed keys every 100ms. If the IR timeout
is set to less than that, we send key up events before the repeat
arrives, so we have key up/key down for each IR repeat.

The keyboard ends any sequence with a 0 scancode, in which case all keys
are cleared so there is no need to run the timeout timer: it only exists
for the case that the final 0 was not received.

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