usb: dwc3: keystone: drop dma_mask configuration

The Keystone 2 supports DT-boot only, as result dma_mask will be
always configured properly from DT -
of_platform_device_create_pdata()->of_dma_configure(). More over,
dwc3-keystone.c can be built as module and in this case it's unsafe to
assign local variable as dma_mask.

Hence, remove dma_mask configuration code.

Cc: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/dwc3-keystone.c

@@ -39,8 +39,6 @@
 #define USBSS_IRQ_COREIRQ_EN	BIT(0)
 #define USBSS_IRQ_COREIRQ_CLR	BIT(0)
 
-static u64 kdwc3_dma_mask;
-
 struct dwc3_keystone {
 	struct device			*dev;
 	struct clk			*clk;
@@ -108,9 +106,6 @@ static int kdwc3_probe(struct platform_device *pdev)
 	if (IS_ERR(kdwc->usbss))
 		return PTR_ERR(kdwc->usbss);
 
-	kdwc3_dma_mask = dma_get_mask(dev);
-	dev->dma_mask = &kdwc3_dma_mask;
-
 	kdwc->clk = devm_clk_get(kdwc->dev, "usb");
 
 	error = clk_prepare_enable(kdwc->clk);