[PATCH] armv6: invalidate cache on DMA_FROM_DEVICE/DMA_BIDIRECTIONAL

[Jamie Iles]

I've just noticed that we can also defer the invalidation from the
v6_dma_map_area to v6_dma_unmap_area. The following patch cleans the cache
for DMA_TO_DEVICE and DMA_BIDIRECTIONAL on mapping but does no invalidation.