isci: removing the kmalloc in smp request construct

It doesn't look like there is any reason to do a kmalloc. We can do the
byte swap in place and avoid the allocation. This allow us to remove
a kmalloc and a memcpy.

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