usb: dwc3: allocate setup_buf with dma_alloc_coherent()

usb: dwc3: allocate setup_buf with dma_alloc_coherent()

Since setup_buf is also consumed by hardware DMA, aligns it's
allocation like other hardware buffers by introduce setup_buf_addr
populated by dma_alloc_coherent(), and use it to pass the physical
address of the buffer to the hardware.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>