staging: comedi: das1800: prefer kmalloc_array over kmalloc with multiply

Checkpatch doesn't like kmalloc with multiply very much:
drivers/staging/comedi/drivers/das1800.c:1377: WARNING: Prefer kmalloc_array over kmalloc with multiply

So this patch swaps that use out for kmalloc_array instead.
Signed-off-by: NChase Southwood <chase.southwood@gmail.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das1800.c

@@ -1374,7 +1374,7 @@ static int das1800_attach(struct comedi_device *dev,
 	if (dev->irq & it->options[2])
 		das1800_init_dma(dev, it);
 
-	devpriv->fifo_buf = kmalloc(FIFO_SIZE * sizeof(uint16_t), GFP_KERNEL);
+	devpriv->fifo_buf = kmalloc_array(FIFO_SIZE, sizeof(uint16_t), GFP_KERNEL);
 	if (!devpriv->fifo_buf)
 		return -ENOMEM;