usb: gadget: USB_R8A66597 should depend on HAS_DMA

If NO_DMA=y:

drivers/built-in.o: In function `sudmac_free_channel':
drivers/usb/gadget/r8a66597-udc.c:676: undefined reference to `usb_gadget_unmap_request'
drivers/built-in.o: In function `sudmac_alloc_channel':
drivers/usb/gadget/r8a66597-udc.c:666: undefined reference to `usb_gadget_map_request'

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