ath10k: fill max_num_vdevs for wmi-tlv

Recent commit
30c78167 ("ath10k:
set max_num_vdevs based on wmi op version")
skipped wmi-tlv case and left max_num_vdevs reset.
Make sure it is properly set.

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