staging: comedi: ni_660x: (!foo) preferred over (foo == NULL)

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/ni_660x.c

@@ -702,7 +702,7 @@ static int ni_660x_request_mite_channel(struct comedi_device *dev,
 	BUG_ON(counter->mite_chan);
 	mite_chan = mite_request_channel(devpriv->mite,
 					 mite_ring(devpriv, counter));
-	if (mite_chan == NULL) {
+	if (!mite_chan) {
 		spin_unlock_irqrestore(&devpriv->mite_channel_lock, flags);
 		dev_err(dev->class_dev,
 			"failed to reserve mite dma channel for counter\n");
@@ -861,7 +861,7 @@ static int ni_660x_alloc_mite_rings(struct comedi_device *dev)
 		for (j = 0; j < counters_per_chip; ++j) {
 			devpriv->mite_rings[i][j] =
 			    mite_alloc_ring(devpriv->mite);
-			if (devpriv->mite_rings[i][j] == NULL)
+			if (!devpriv->mite_rings[i][j])
 				return -ENOMEM;
 		}
 	}
@@ -1107,7 +1107,7 @@ static int ni_660x_auto_attach(struct comedi_device *dev,
 						     ni_gpct_variant_660x,
 						     ni_660x_num_counters
 						     (dev));
-	if (devpriv->counter_dev == NULL)
+	if (!devpriv->counter_dev)
 		return -ENOMEM;
 	for (i = 0; i < NI_660X_MAX_NUM_COUNTERS; ++i) {
 		s = &dev->subdevices[NI_660X_GPCT_SUBDEV(i)];