ath10k: fix wmm params per vdev

During wmm tests changing wmm parameters did not change anything.
This was because of mismatch in WMM params per vdev command.
WMM params per vdev uses different command structure than wmm params
per pdev command.

Patch concerns qca6174.

Signed-off-by: Marek Puzyniak <marek.puzyniak@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>