wifi: ath12k: Add helper to free DP link peer

wifi: ath12k: Add helper to free DP link peer

Introduce ath12k_dp_link_peer_free() to wrap cleanup steps required before
freeing a DP link peer. This avoids code duplication and ensures consistent
teardown across multiple call flows.

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

Signed-off-by: Pavankumar Nandeshwar <quic_pnandesh@quicinc.com>
Signed-off-by: Ripan Deuri <quic_rdeuri@quicinc.com>
Reviewed-by: Karthikeyan Periyasamy <karthikeyan.periyasamy@oss.qualcomm.com>
Reviewed-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>
Link: https://patch.msgid.link/20251103112111.2260639-5-quic_rdeuri@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>