usb: dwc3: use bus->sysdev for DMA configuration

The dma ops for dwc3 devices are not set properly. So, use a
physical device sysdev, which will be inherited from parent,
to set the hardware / firmware parameters like dma.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sriram Dash <sriram.dash@nxp.com>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>