usb: musb: ux500: take the dma_mask from coherent_dma_mask

The dma_mask will always be the same as the coherent_dma_mask, so let's
cut down on the platform_data burden and set it as such in the driver.
This also saves us from supporting it separately when we come to enable
this driver for Device Tree.

Cc: [e-mail]
Acked-by: Felipe Balbi <[e-mail]>
Acked-by: Fabio Baltieri <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

arch/arm/mach-ux500/usb.c

···
 	.dma_filter = stedma40_filter,
 };
 
-static u64 ux500_musb_dmamask = DMA_BIT_MASK(32);
-
 static struct musb_hdrc_platform_data musb_platform_data = {
 	.mode = MUSB_OTG,
 	.board_data = &musb_board_data,
···
 	.id = 0,
 	.dev = {
 		.platform_data = &musb_platform_data,
-		.dma_mask = &ux500_musb_dmamask,
 		.coherent_dma_mask = DMA_BIT_MASK(32),
 	},
 	.num_resources = ARRAY_SIZE(usb_resources),

drivers/usb/musb/ux500.c

···
 	}
 
 	musb->dev.parent		= &pdev->dev;
-	musb->dev.dma_mask		= pdev->dev.dma_mask;
+	musb->dev.dma_mask		= &pdev->dev.coherent_dma_mask;
 	musb->dev.coherent_dma_mask	= pdev->dev.coherent_dma_mask;
 
 	glue->dev			= &pdev->dev;