IB/hfi1: Check for QSFP presence before attempting reads

Attempting to read the status of a QSFP cable creates noise in the logs
and misses out on setting an appropriate Offline/Disabled Reason if the
cable is not plugged in. Check for this prior to attempting the read and
attendant retries.

Fixes: 673b975f ("IB/hfi1: Add QSFP sanity pre-check")
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Easwar Hariharan <easwar.hariharan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>