wifi: ath12k: fix dp_link_peer dangling references on AP vdev rollback

In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix dp_link_peer dangling references on AP vdev rollback ath12k_mac_vdev_create() for an AP vdev creates the bss self-peer via ath12k_peer_create(), which finishes by calling ath12k_dp_link_peer_assign() to publish the dp_link_peer in the dp_hw->dp_peers[peerid_index] RCU table, in the dp_peer's link_peers[] array, and in the per-addr rhashtable. If a step after ath12k_peer_create() fails the function jumps to err_peer_del, which open-codes a WMI peer_delete and waits for the unmap / delete_resp events. The wait_for_peer_delete_done() path relies on ath12k_dp_link_peer_unmap_event() freeing the dp_link_peer when the unmap arrives, but err_peer_del never calls ath12k_dp_link_peer_unassign() first. The published references in the dp_hw RCU table, dp_peer->link_peers[] and the rhashtable are left pointing at the dp_link_peer that unmap_event then frees, producing dangling pointers and use-after-free on subsequent lookups. Replace the open-coded sequence with a call to ath12k_peer_delete(), which already does ath12k_dp_link_peer_unassign() before sending the WMI command. This drops the published references before the dp_link_peer is freed, in the same order as the normal teardown path in ath12k_mac_remove_link_interface(). Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3