modules: hostap: Fix the SoF in iface_wq

In case interface is UP, the interface is added to WPA supplicant in the
iface_wq itself and the max stack size is 4264, so, increase the stack
size of the iface_wq.

If the interface is added via net_mgmt thread then it works fine.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>