[csl] fix indirect retransmission of frame previously transmitted via…

… CSL (#8770)

Bug fix for an issue where any frame which fails CSL transmission gets
treated as a new frame (instead of a retransmission) for a subsequent
indirect retransmission (in the data poll handler). This fix checks
for the previous CSL transmit attempts and if it is greater than 0,
retransmits with the same frame counter, sequence number and key id as
previous attempt.

src/core/mac/data_poll_handler.cpp

@@ -188,7 +188,11 @@ Mac::TxFrame *DataPollHandler::HandleFrameRequest(Mac::TxFrames &aTxFrames)
     VerifyOrExit(mCallbacks.PrepareFrameForChild(*frame, mFrameContext, *mIndirectTxChild) == kErrorNone,
                  frame = nullptr);
 
+#if OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE
+    if ((mIndirectTxChild->GetIndirectTxAttempts() > 0) || (mIndirectTxChild->GetCslTxAttempts() > 0))
+#else
     if (mIndirectTxChild->GetIndirectTxAttempts() > 0)
+#endif
     {
         // For a re-transmission of an indirect frame to a sleepy
         // child, we ensure to use the same frame counter, key id, and