usb: gadget: udc: USB_GADGET_XILINX should depend on HAS_DMA

usb: gadget: udc: USB_GADGET_XILINX should depend on HAS_DMA

If NO_DMA=y:

drivers/built-in.o: In function `xudc_done':
udc-xilinx.c:(.text+0x54f4d2): undefined reference to `usb_gadget_unmap_request'
drivers/built-in.o: In function `xudc_dma_send':
udc-xilinx.c:(.text+0x54f9f8): undefined reference to `dma_sync_single_for_cpu'
drivers/built-in.o: In function `xudc_read_fifo':
udc-xilinx.c:(.text+0x54ff4a): undefined reference to `dma_sync_single_for_cpu'
drivers/built-in.o: In function `xudc_ep_queue':
udc-xilinx.c:(.text+0x550e7c): undefined reference to `usb_gadget_map_request'

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