isci: make function declaration match implementation

Sparse complains that we redeclare this with a different type, because
in the .c file we use an enum and in the .h file we declare the
parameter as a u32.  Probably it's best to use an enum in both places.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>