IB/hfi1: On error, fix use after free during user context setup

During base context setup, if setup_base_ctxt() fails, the context is
deallocated. This is incorrect because the context is referenced on
return, to notify any waiting subcontext.  If there are no subcontexts
the pointer will be invalid.

Reorganize the error path so that deallocate_ctxt() is called after all
the possible subcontexts have been notified.

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