staging/hfi1: Remove unneeded variable index

The variable "index" increments the same as dd->ndevcntrs.
Just use the later.  Remove uneeded usage of "index" in the
fill loop - it is not used there or later in the function.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>