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

Signed-off-by: Rajat Soni <quic_rajson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230315090632.15065-1-quic_rajson@quicinc.com