[PATCH Comedilib] comedi_test: test_cmd_write_fast_1chan writes too much data

Hi,

I was running "comedi_test -v" on my new analog output driver and 
noticed that it was getting stuck in a loop during the 
"cmd_write_fast_1_chan" test.

It turned out that the test had written more data to the buffer than was 
required to complete the acquisition (it was using cmd->stop_src = 
TRIG_COUNT) and then got stuck in a loop waiting for the buffer to empty.

The attached patch stops the test_cmd_write_fast_1chan function writing 
more data than is required to complete the acquisition.

-- 
-=( Ian Abbott _at_ MEV Ltd.    E-mail: <abbotti_at_mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-