staging: comedi: ni_at_ao: tidy up atao_attach()

For aesthetics, add some whitespace to the subdevice init.

Remove the printk noise at the end of the attach.

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>