V4L/DVB: gspca - main: Fix a crash of some webcams on ARM arch

When plugging some webcams on ARM, the system crashes.
This is because we alloc buffer for an urb through usb_buffer_alloc,
the alloced buffer is already in DMA coherent region, so we should
set the flag of this urb to URB_NO_TRANSFER_DMA_MAP, otherwise when
we submit this urb, the hcd core will handle this address as an
non-DMA address and call dma_map_single/sg to map it. On arm
architecture, dma_map_single a DMA coherent address will be catched
by a BUG_ON().
Signed-off-by: Jason Wang <jason77.wang@gmail.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/gspca.c

@@ -223,6 +223,7 @@ static int alloc_and_submit_int_urb(struct gspca_dev *gspca_dev,
 		usb_rcvintpipe(dev, ep->bEndpointAddress),
 		buffer, buffer_len,
 		int_irq, (void *)gspca_dev, interval);
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	gspca_dev->int_urb = urb;
 	ret = usb_submit_urb(urb, GFP_KERNEL);
 	if (ret < 0) {