net/ethernet: MACB should depend on HAS_DMA

If NO_DMA=y:

drivers/built-in.o: In function `macb_free_consistent':
drivers/net/ethernet/cadence/macb.c:878: undefined reference to `dma_free_coherent'
drivers/net/ethernet/cadence/macb.c:883: undefined reference to `dma_free_coherent'
drivers/net/ethernet/cadence/macb.c:888: undefined reference to `dma_free_coherent'
drivers/built-in.o: In function `macb_alloc_consistent':
drivers/net/ethernet/cadence/macb.c:905: undefined reference to `dma_alloc_coherent'
drivers/built-in.o: In function `macb_tx_interrupt':
drivers/net/ethernet/cadence/macb.c:515: undefined reference to `dma_unmap_single'
drivers/built-in.o: In function `macb_tx_error_task':
drivers/net/ethernet/cadence/macb.c:457: undefined reference to `dma_unmap_single'
drivers/built-in.o: In function `macb_start_xmit':
drivers/net/ethernet/cadence/macb.c:838: undefined reference to `dma_map_single'

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>