staging: comedi: ni_at_ao: fix board names

This driver works with "at-ao-6/10" boards not "ai-ao-6/10" boards.
Fix the names in the boardinfo.

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>