DMA-API: usb: use dma_set_coherent_mask()

The correct way for a driver to specify the coherent DMA mask is
not to directly access the field in the struct device, but to use
dma_set_coherent_mask().  Only arch and bus code should access this
member directly.

Convert all direct write accesses to using the correct API.

Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/usb/host/ohci-at91.c

@@ -524,7 +524,7 @@ MODULE_DEVICE_TABLE(of, at91_ohci_dt_ids);
 static int ohci_at91_of_init(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
-	int i, gpio;
+	int i, gpio, ret;
 	enum of_gpio_flags flags;
 	struct at91_usbh_data	*pdata;
 	u32 ports;
@@ -538,8 +538,9 @@ static int ohci_at91_of_init(struct platform_device *pdev)
 	 */
 	if (!pdev->dev.dma_mask)
 		pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
-	if (!pdev->dev.coherent_dma_mask)
-		pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+	if (ret)
+		return ret;
 
 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)