usb: gadget: udc: USB_SNP_CORE should depend on HAS_DMA

If NO_DMA=y:

    ERROR: "usb_gadget_map_request" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!
    ERROR: "dma_pool_destroy" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!
    ERROR: "usb_gadget_unmap_request" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!
    ERROR: "dma_pool_free" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!
    ERROR: "dma_pool_alloc" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!
    ERROR: "dma_pool_create" [drivers/usb/gadget/udc/snps_udc_core.ko] undefined!

As USB_SNP_CORE is selected by USB_SNP_UDC_PLAT and USB_AMD5536UDC,
these should depend on HAS_DMA, too.  For USB_AMD5536UDC, this is
already fulfilled through the dependency on USB_PCI (PCI implies
HAS_DMA).

Add dependencies on HAS_DMA to fix this.

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