staging: comedi: aio_aio12_8: rename 'aio_ao12_8' boardinfo

This board name is incorrect. The proper name is 104-AO12-4.

Change the boardinfo name to 'aio_aio12_4' to follow the format of
the other boardtypes.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>