ath10k: advertise more conservative intf combinations

Apparently the available firmware has a limit of
handling 7 APs, 3 GOs or 8 STAs. This is based on
empirical tests and it is still possible some
combinations may crash the firmware.

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