cross-tree: phase out dma_zalloc_coherent() on headers

The last few stragglers coccinelle doesn't pick up are on driver
specific header files. Phase those out as well as dma_alloc_coherent()
zeroes out the memory as well now too.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>