wifi: ath12k: fix memory leak in ath12k_qmi_driver_event_work()

In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix memory leak in ath12k_qmi_driver_event_work() Currently the buffer pointed by event is not freed in case ATH12K_FLAG_UNREGISTERING bit is set, this causes memory leak. Add a goto skip instead of return, to ensure event and all the list entries are freed properly. Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1