linux-phytec-ti

mtip32xx: don't use req->special

Instead create add to the icmd into struct mtip_cmd which can be unioned
with the scatterlist used for the normal I/O path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>