crypto: caam - Remove GFP_DMA and add DMA alignment padding

GFP_DMA does not guarantee that the returned memory is aligned
for DMA.  It should be removed where it is superfluous.

However, kmalloc may start returning DMA-unaligned memory in future
so fix this by adding the alignment by hand.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>