staging: comedi: use CMDF_BOGUS in do_cmd_ioctl()

`TRIG_BOGUS` is now just a synonym for `CMDF_BOGUS`.  Change
`do_cmd_ioctl()` to use the new name.

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