The caam driver use two dma_map_sg path according to SG are chained
or not.
Since dma_map_sg can handle both case, clean the code with all
references to sg chained.

Thus removing dma_map_sg_chained, dma_unmap_sg_chained
and __sg_count functions.
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>