wifi: mac80211_hwsim: add back erroneously removed cast

The robots report that we're now casting to a differently
sized integer, which is correct, and the previous patch
had erroneously removed it.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 4ee186fa ("wifi: mac80211_hwsim: fix race condition in pending packet")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -4210,7 +4210,7 @@ static int hwsim_tx_info_frame_received_nl(struct sk_buff *skb_2,
 		u64 skb_cookie;
 
 		txi = IEEE80211_SKB_CB(skb);
-		skb_cookie = (u64)txi->rate_driver_data[0];
+		skb_cookie = (u64)(uintptr_t)txi->rate_driver_data[0];
 
 		if (skb_cookie == ret_skb_cookie) {
 			__skb_unlink(skb, &data2->pending);