wifi: ath12k: Fix memory leak during extended skb allocation

wifi: ath12k: Fix memory leak during extended skb allocation

In ath12k_dp_tx(), memory allocated for extended skb is not freed
properly, causing a memory leak even when the host receives tx
completion for those skbs. Fix this issue by storing skb_ext_desc
in the host tx descriptor and using this skb_ext_desc field during
completion or during ath12k_dp_cc_cleanup().

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: P Praneesh <praneesh.p@oss.qualcomm.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250411060154.1388159-4-praneesh.p@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>