staging: comedi: adl_pci9118: TRIG_INT is not vaild for scan_begin_src

The (*do_cmdtest) in this driver validated the scan_begin_src as being
TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT. The TRIG_INT source is not valid.

Remove the Step 2 mutual compatibility check that makes sure that TRIG_INT
is only used for the start_src or the scan_begin_src.

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>