IB/hfi1: Avoid credit return allocation for cpu-less NUMA nodes

Do not allocate credit return base and DMA memory for
NUMA nodes without CPUs.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>