staging: comedi: das16m1: remove unnecessary ai 'cancel' operations

The comedi core will only call the (*insn_read) and (*do_cmd) functions
if the subdevice is not "busy". All async commands are terminated by
a (*cancel) operation which clears the INTE and PACER_MASK bits in the
interrupt control register. These bits are also cleared when the driver
first attaches. There is no need for the (*insn_read) or (*do_cmd) to
duplicate the cancel.
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/das16m1.c

@@ -226,10 +226,6 @@ static int das16m1_cmd_exec(struct comedi_device *dev,
 	struct comedi_cmd *cmd = &async->cmd;
 	unsigned int byte, i;
 
-	/* disable interrupts and internal pacer */
-	devpriv->control_state &= ~INTE & ~PACER_MASK;
-	outb(devpriv->control_state, dev->iobase + DAS16M1_INTR_CONTROL);
-
 	/*  set software count */
 	devpriv->adc_count = 0;
 
@@ -313,15 +309,10 @@ static int das16m1_ai_rinsn(struct comedi_device *dev,
 			    struct comedi_subdevice *s,
 			    struct comedi_insn *insn, unsigned int *data)
 {
-	struct das16m1_private_struct *devpriv = dev->private;
 	int ret;
 	int n;
 	int byte;
 
-	/* disable interrupts and internal pacer */
-	devpriv->control_state &= ~INTE & ~PACER_MASK;
-	outb(devpriv->control_state, dev->iobase + DAS16M1_INTR_CONTROL);
-
 	/* setup channel/gain queue */
 	outb(0, dev->iobase + DAS16M1_QUEUE_ADDR);
 	byte =