staging: comedi: das1800: reduce indent level of das1800_init_dma()

An IRQ and at least one DMA channel are required to use DMA with this driver.
Move the check to the caller to reduce the indent level of this function.
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/das1800.c

@@ -1240,8 +1240,6 @@ static int das1800_init_dma(struct comedi_device *dev, unsigned int dma0,
 	struct das1800_private *devpriv = dev->private;
 	unsigned long flags;
 
-	/*  need an irq to do dma */
-	if (dev->irq && dma0) {
 	/* encode dma0 and dma1 into 2 digit hexadecimal for switch */
 	switch ((dma0 & 0x7) | (dma1 << 4)) {
 	case 0x5:	/*  dma0 == 5 */
@@ -1305,7 +1303,7 @@ static int das1800_init_dma(struct comedi_device *dev, unsigned int dma0,
 		set_dma_mode(devpriv->dma1, DMA_MODE_READ);
 	}
 	release_dma_lock(flags);
-	}
+
 	return 0;
 }
 
@@ -1437,9 +1435,12 @@ static int das1800_attach(struct comedi_device *dev,
 		}
 	}
 
+	/* an irq and one dma channel is required to use dma */
+	if (dev->irq & dma0) {
 		ret = das1800_init_dma(dev, dma0, dma1);
 		if (ret < 0)
 			return ret;
+	}
 
 	if (devpriv->ai_buf0 == NULL) {
 		devpriv->ai_buf0 =