isci: Convert of sci_ssp_response_iu to ssp_response_iu

Converting to Linux native format. However the isci driver does a lot of
the calculation based on the max size of this data structure and the
Linux data structure only has a pointer to the response data. Thus the
sizeof(struct ssp_response_iu) will be incorrect and we need to define
the max size.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>