ethernet: amd: AMD_XGBE should depend on HAS_DMA

If NO_DMA=y:

    drivers/built-in.o: In function `xgbe_probe':
    xgbe-main.c:(.text+0x2def0a): undefined reference to `dma_set_mask'
    xgbe-main.c:(.text+0x2def20): undefined reference to `dma_supported'
    drivers/built-in.o: In function `xgbe_rx_poll':
    xgbe-drv.c:(.text+0x2e0320): undefined reference to `dma_sync_single_for_cpu'
    xgbe-drv.c:(.text+0x2e035e): undefined reference to `dma_sync_single_for_cpu'
    drivers/built-in.o: In function `xgbe_unmap_rdata':
    xgbe-desc.c:(.text+0x2e5fe4): undefined reference to `dma_unmap_page'
    xgbe-desc.c:(.text+0x2e5ffa): undefined reference to `dma_unmap_single'
    xgbe-desc.c:(.text+0x2e604a): undefined reference to `dma_unmap_page'
    xgbe-desc.c:(.text+0x2e6084): undefined reference to `dma_unmap_page'
    drivers/built-in.o: In function `xgbe_alloc_pages':
    xgbe-desc.c:(.text+0x2e6156): undefined reference to `dma_map_page'
    xgbe-desc.c:(.text+0x2e6164): undefined reference to `dma_mapping_error'
    drivers/built-in.o: In function `xgbe_free_ring':
    xgbe-desc.c:(.text+0x2e63d4): undefined reference to `dma_unmap_page'
    xgbe-desc.c:(.text+0x2e640e): undefined reference to `dma_unmap_page'
    xgbe-desc.c:(.text+0x2e644a): undefined reference to `dma_free_coherent'
    drivers/built-in.o: In function `xgbe_init_ring':
    xgbe-desc.c:(.text+0x2e64d4): undefined reference to `dma_alloc_coherent'
    drivers/built-in.o: In function `xgbe_map_tx_skb':
    xgbe-desc.c:(.text+0x2e6628): undefined reference to `dma_map_single'
    xgbe-desc.c:(.text+0x2e6638): undefined reference to `dma_mapping_error'
    xgbe-desc.c:(.text+0x2e66b2): undefined reference to `dma_map_single'
    xgbe-desc.c:(.text+0x2e66c2): undefined reference to `dma_mapping_error'
    xgbe-desc.c:(.text+0x2e6762): undefined reference to `dma_map_page'
    xgbe-desc.c:(.text+0x2e6772): undefined reference to `dma_mapping_error'

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>