staging: comedi: me4000: remove unnecessary me4000_ai_cancel()

The comedi core ensures that the subdevice is not busy before it allows
starting a new command. The subdevice (*cancel) is called when the
subdevice is set to not busy. In this driver the me4000_ai_cancel()
is the ai (*cancel) so the extra call in the ai (*do_cmd) is not
necessary. Remove it.
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>

drivers/staging/comedi/drivers/me4000.c

@@ -665,12 +665,6 @@ static int me4000_ai_do_cmd(struct comedi_device *dev,
 	struct me4000_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
 	unsigned int ctrl;
-	int err;
-
-	/* Reset the analog input */
-	err = me4000_ai_cancel(dev, s);
-	if (err)
-		return err;
 
 	/* Write timer arguments */
 	outl(devpriv->ai_init_ticks - 1,