ARM: shmobile: bockw: fixup DMA mask

ARM: shmobile: bockw: fixup DMA mask

4dcfa60071b3d23f0181f27d8519f12e37cefbb9
(ARM: DMA-API: better handing of DMA masks for coherent allocations)
exchanged DMA mask check method.
Below warning will appear without this patch

asoc-simple-card asoc-simple-card.0: \
  Coherent DMA mask 0xffffffffffffffff is larger than dma_addr_t allows
asoc-simple-card asoc-simple-card.0: \
  Driver did not use or check the return value from dma_set_coherent_mask()?

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>