ARM: shmobile: BOCK-W: set proper DMA masks for Ether device

Ether MAC is a DMA-capable device and so should have 'dev.dma_mask' and
'dev.coherent_dma_mask' fields set properly, to reflect 32-bit DMA addressing
ability.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>