ath10k: add the WMI Air Time Fairness service define

Add the FW ATF (Air Time Fairness) service define to keep consistent
with 10.2 FW capability.

Signed-off-by: Yanbo Li <yanbol@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>