staging: comedi: ni_mio_common: use cfc_check_trigger_arg_*() helpers

Use the new helpers in the step 3 tests of ni_{ai,ao,cdio}_cmdtest().

Note that all the command triggers in ni_cdio_cmdtest are single source
so the extra tests are not required.

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