IB/hfi1: Remove unused variable from devdata

We no longer use an error tasklet. Remove it from the hfi1_devdata
structure.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>