wifi: ath11k: remove unused function ath11k_tm_event_wmi()

The function ath11k_tm_event_wmi() is only defined and it is not used
anywhere. Hence remove the unused.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1

Signed-off-by: Govindaraj Saminathan <quic_gsaminat@quicinc.com>
Signed-off-by: Raj Kumar Bhagat <quic_rajkbhag@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230517135934.16408-2-quic_rajkbhag@quicinc.com