staging: comedi: adv_pci1710: don't check the chanlist twice
staging: comedi: adv_pci1710: don't check the chanlist twice

The chanlist is checked in Step 5 of the (*do_cmdtest) there is no
reason to check it again in the (*do_cmd). The only reason its done
again is to get the actual 'seglen', the non-repeating length of the
chanlist.

Save the 'seglen' found by pci171x_ai_check_chanlist() in the private
data and use that in the (*do_cmd). Rename the private data member to
clarify it. Also, remove the unused 'act_chanlist_pos' member from the
private data.

Refactor the error handling in pci171x_ai_check_chanlist() so it returns
and errno for failure and 0 for success.

Signed-off-by: H Hartley Sweeten <382ff55d8e07d1082d179e669636cd1552da4f36@visionengravers.com>
Reviewed-by: Ian Abbott <9e6ba6483b6a3e14d61f7c987e72ecb5b46122d6@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs