IB/hfi1: Protect the global dev_cntr_names and port_cntr_names

Protect the global dev_cntr_names and port_cntr_names with the global
mutex as they are allocated and freed in a function called per device.
Otherwise there is a danger of double free and memory leaks.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@intel.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>