Input: atkbd - make dmi callback functions return 1

We only care about if there is a successful match from the table (or
no match at all), so let's make dmi_check_system return immediately
instead of iterating thorough the whole table.

Make the dmi callback function return 1 then dmi_check_system
will return immediately if we have a successful match.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>