Clear tp->tod in t4_pcb_detach().

[jhb]

Summary

Otherwise, a socket can have a non-NULL tp->tod while TF_TOE is clear.
In particular, if a newly accepted socket falls back to non-TOE due to
an active open failure, the non-TOE socket will still have tp->tod set
even though TF_TOE is clear.

Test Plan

• tested some TOE TLS workloads with this patch in place

head/sys/dev/cxgbe/tom/t4_tom.c

#ifdef KTR
         } else {
                 CTR6(KTR_CXGBE,
                     "t4_pcb_detach: tid %d (%s), toep %p (0x%x), inp %p (0x%x)",
                     toep->tid, tcpstates[tp->t_state], toep, toep->flags, inp,
                     inp->inp_flags);
         }
 #endif
 
+        tp->tod = NULL;
         tp->t_toe = NULL;
         tp->t_flags &= ~TF_TOE;
         toep->flags &= ~TPF_ATTACHED;
 
         if (!(toep->flags & TPF_CPL_PENDING))
                 release_offload_resources(toep);
 }