mac80211: Add support for BSS max idle period element

Parse the BSS max idle period element and set the BSS configuration
accordingly so the driver can use this information to configure the
max idle period and to use protected management frames for keep alive
when required.

The BSS max idle period element is defined in IEEE802.11-2016,
section 9.4.2.79

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 2a57305..f8f6c14 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1483,6 +1483,7 @@ struct ieee802_11_elems {
 	const u8 *opmode_notif;
 	const struct ieee80211_sec_chan_offs_ie *sec_chan_offs;
 	const struct ieee80211_mesh_chansw_params_ie *mesh_chansw_params_ie;
+	const struct ieee80211_bss_max_idle_period_ie *max_idle_period_ie;
 
 	/* length of them, respectively */
 	u8 ext_capab_len;