usb: gadget: USB_MV_U3D should depend on HAS_DMA

If NO_DMA=y:

drivers/built-in.o: In function `mv_u3d_done':
drivers/usb/gadget/mv_u3d_core.c:206: undefined reference to `dma_pool_free'
drivers/usb/gadget/mv_u3d_core.c:209: undefined reference to `dma_unmap_single'
drivers/built-in.o: In function `mv_u3d_build_trb_one':
drivers/usb/gadget/mv_u3d_core.c:311: undefined reference to `dma_pool_alloc'
drivers/built-in.o: In function `mv_u3d_req_to_trb':
drivers/usb/gadget/mv_u3d_core.c:480: undefined reference to `dma_map_single'
drivers/built-in.o: In function `mv_u3d_remove':
drivers/usb/gadget/mv_u3d_core.c:1770: undefined reference to `dma_pool_destroy'
drivers/usb/gadget/mv_u3d_core.c:1773: undefined reference to `dma_free_coherent'
drivers/built-in.o: In function `mv_u3d_probe':
drivers/usb/gadget/mv_u3d_core.c:1880: undefined reference to `dma_alloc_coherent'
drivers/usb/gadget/mv_u3d_core.c:1890: undefined reference to `dma_pool_create'
drivers/usb/gadget/mv_u3d_core.c:1984: undefined reference to `dma_pool_destroy'
drivers/usb/gadget/mv_u3d_core.c:1986: undefined reference to `dma_free_coherent'

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>