IB/hfi1: Change default number of user contexts

Change the default number of user contexts to the number of real
(non-HT) cpu cores in order to reduce the division of hfi1 hardware
contexts in the case of high core counts with hyper-threading enabled.

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