usb: Fix incorrect default DMA offset.

The default DMA offset is set to 3. When the property is not set by
the consumer, the default causes DMA access to be shifted by 3
bytes. In PXA, this results in incorrect DMA access, leading to error
notification in the USB controller driver. A better default would be
0, so that there is no offset, when the consumer does not specify one.

Signed-off-by: Vijay Kumar B. <vijaykumar@zilogic.com>
Reviewed-by: Deepak S. <deepak@zilogic.com>
Message-id: 1475060958-7760-1-git-send-email-vijaykumar@zilogic.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>