ath10k: suppress warnings when getting wmi peer_rate_code_list event

In 10.4, fw sends WMI PEER_RATECODE_LIST_EVENTID after successful
peer_assoc cmd. As of now this event is not of much use and not
implemented. Change the debug level and messsage as appropriate
to suppress "Unknown eventid: 36898".

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>