ath10k: move wmm param storage to vif

mac80211 already requests WMM per vif but firmware
wasn't able to handle this until now. However new
wmi-tlv firmware for qca6174 is capable of this.

This prepares per-vif WMM param setup.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>