hostap: Use proper value when generating supplicant event

The previous NET_EVENT_SUPPLICANT_CMD_INT_EVENT is from
"enum net_event_supplicant_cmd" but the supplicant_send_wifi_mgmt_event()
has the event parameter as an "enum net_event_wifi_cmd" and those event
number spaces are different.

This meant that the wrong event value NET_EVENT_SUPPLICANT_CMD_INT_EVENT
maps to NET_EVENT_WIFI_CMD_TWT (from "enum net_event_wifi_cmd") which
fortunately did not cause issue in this case because the
supplicant_send_wifi_mgmt_event() has no handling for this TWT event value.

It is important we fix this as this can cause great confusion in the
future.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>