usb: musb: do not change dev's dma_mask

Commit 8d2421e ("usb: musb: kill global and static for multi instance")
removed the global dma_mask copy and replaced by parent's DMA mask. The
problem here is that if the parent does not have a dma_mask then
musb_remove() goes kaboom.
Instead trying to fix this I was thinking we do we need to erase
dma_mask in the first place?

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -1843,10 +1843,6 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 	if (use_dma && dev->dma_mask)
 		musb->dma_controller = dma_controller_create(musb, musb->mregs);
 
-	/* ideally this would be abstracted in platform setup */
-	if (!musb->dma_controller)
-		dev->dma_mask = NULL;
-
 	/* be sure interrupts are disabled before connecting ISR */
 	musb_platform_disable(musb);
 	musb_generic_disable(musb);
@@ -1993,9 +1989,6 @@ static int musb_remove(struct platform_device *pdev)
 
 	musb_free(musb);
 	device_init_wakeup(dev, 0);
-#ifndef CONFIG_MUSB_PIO_ONLY
-	dma_set_mask(dev, *dev->parent->dma_mask);
-#endif
 	return 0;
 }