To not exceed number of allowed clients (AP mode), make sure to
check how many of them are already on the peers list.

10.X firmware support up to 127 peers, non-AP centric firmwares 16.
Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>