ath10k: remove unused variable ar_pci

Trival fix to remove unused variable ar_pci in ath10k_pci_tx_pipe_cleanup
when building with W=1:
drivers/net/wireless/ath/ath10k/pci.c:1696:21: warning: variable
'ar_pci' set but not used [-Wunused-but-set-variable]
Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/pci.c

@@ -1691,14 +1691,12 @@ static void ath10k_pci_rx_pipe_cleanup(struct ath10k_pci_pipe *pci_pipe)
 static void ath10k_pci_tx_pipe_cleanup(struct ath10k_pci_pipe *pci_pipe)
 {
 	struct ath10k *ar;
-	struct ath10k_pci *ar_pci;
 	struct ath10k_ce_pipe *ce_pipe;
 	struct ath10k_ce_ring *ce_ring;
 	struct sk_buff *skb;
 	int i;
 
 	ar = pci_pipe->hif_ce_state;
-	ar_pci = ath10k_pci_priv(ar);
 	ce_pipe = pci_pipe->ce_hdl;
 	ce_ring = ce_pipe->src_ring;