dmaengine: stm32-dmamux: Switch to use device_property_count_u32()

Use use device_property_count_u32() directly, that makes code neater.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190723190757.67351-1-andriy.shevchenko@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/stm32-dmamux.c

@@ -185,8 +185,7 @@ static int stm32_dmamux_probe(struct platform_device *pdev)
 	if (!node)
 		return -ENODEV;
 
-	count = device_property_read_u32_array(&pdev->dev, "dma-masters",
-					       NULL, 0);
+	count = device_property_count_u32(&pdev->dev, "dma-masters");
 	if (count < 0) {
 		dev_err(&pdev->dev, "Can't get DMA master(s) node\n");
 		return -ENODEV;