Redpine: wifi-ap stopped working after restart

[Siva Rebbagondla]

SRU Justification:
------------------

Impact:
    Wi-Fi access point isn’t visible to outside devices after reboot

Test Case:
    Configure Wi-Fi AP using setup wizard:
       $ sudo wifi-ap.setup-wizard

    Check configured AP settings:
       $ sudo wifi-ap.config get

       debug: false
       dhcp.lease-time: 12h
       dhcp.range-start: 10.0.60.2
       dhcp.range-stop: 10.0.60.200
       disabled: false
       share.disabled: false
       share.network-interface: wlan0
       wifi.address: 10.0.60.1
       wifi.channel: 6
       wifi.country-code:
       wifi.hostapd-driver: nl80211
       wifi.interface: wlan0
       wifi.interface-mode: direct
       wifi.netmask: ff000000
       wifi.operation-mode: g
       wifi.security: wpa2
       wifi.security-passphrase: some-password
       wifi.ssid: dell-gateway

    Restart AP and check its status:
       $ sudo wifi-ap.status restart-ap

    Check status of AP. It is showing true.
       $ sudo wifi-ap.status
       ap.active: true

    At this point, Wi-Fi access point is not visible.

Fix:
    Power save is not enabled in AP mode and modified the same in source code.

Regression potential:
    Ran "wifi-ap.status restart-ap" command in every 1 minute and observed whether it is visible to third party devices are not. And it is behaving as expected.

[Siva Rebbagondla (siva8118)]

This duplicate of "https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1773400"