add 256 channels support

[ROCm/rccl commit: 506f16c506]

projects/rccl/src/group.cc

@@ -225,8 +225,10 @@ static void groupCleanup(struct ncclComm** groupCommHeadPtr, struct ncclComm** g
     for (int i = 0; i < comm->nRanks; i++) {
       comm->tasks.peers[i].sendSeen = false;
       comm->tasks.peers[i].recvSeen = false;
-      comm->connectSend[i] = 0UL;
-      comm->connectRecv[i] = 0UL;
+      for (int j = 0; j < 4; j++) {
+      	comm->connectSend[i].masks[j] = 0UL;
+      	comm->connectRecv[i].masks[j] = 0UL;
+      }
     }
     comm->unlaunchedPlansHead = nullptr;
     // Reclaim abandoned kernel plan memory. Note ncclWork structs were already