AP-side workaround for WNM-Sleep Mode GTK/IGTK reinstallation issues

AP-side workaround for WNM-Sleep Mode GTK/IGTK reinstallation issues

Normally, WNM-Sleep Mode exit with management frame protection
negotiated would result in the current GTK/IGTK getting added into the
WNM-Sleep Mode Response frame. Some station implementations may have a
vulnerability that results in GTK/IGTK reinstallation based on this
frame being replayed. Add a new hostapd configuration parameter that can
be used to disable that behavior and use EAPOL-Key frames for GTK/IGTK
update instead. This would likely be only used with
wpa_disable_eapol_key_retries=1 that enables a workaround for similar
issues with EAPOL-Key. This is related to station side vulnerabilities
CVE-2017-13087 and CVE-2017-13088. To enable this AP-side workaround,
set wnm_sleep_mode_no_keys=1.

Signed-off-by: Jouni Malinen <j@w1.fi>