staging: comedi: me4000: fix ai_write_chanlist()

Rename this function so it has namespace associated with the driver.

The last entry of the chanlist needs the ME4000_AI_LIST_LAST_ENTRY bit
set to end the list. Fix the function and tidy if up a bit.

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>