mac80211: fix CSA in IBSS mode

BugLink: http://bugs.launchpad.net/bugs/1702104

commit f181d6a3 upstream.

Add the missing IBSS capability flag during capability init as it needs
to be inserted into the generated beacon in order for CSA to work.

Fixes: cd7760e6 ("mac80211: add support for CSA in IBSS mode")
Signed-off-by: Piotr Gawlowicz <gawlowicz@tkn.tu-berlin.de>
Signed-off-by: Mikołaj Chwalisz <chwalisz@tkn.tu-berlin.de>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

net/mac80211/ibss.c

@@ -486,14 +486,14 @@ int ieee80211_ibss_csa_beacon(struct ieee80211_sub_if_data *sdata,
 	struct beacon_data *presp, *old_presp;
 	struct cfg80211_bss *cbss;
 	const struct cfg80211_bss_ies *ies;
-	u16 capability = 0;
+	u16 capability = WLAN_CAPABILITY_IBSS;
 	u64 tsf;
 	int ret = 0;
 
 	sdata_assert_lock(sdata);
 
 	if (ifibss->privacy)
-		capability = WLAN_CAPABILITY_PRIVACY;
+		capability |= WLAN_CAPABILITY_PRIVACY;
 
 	cbss = cfg80211_get_bss(sdata->local->hw.wiphy, ifibss->chandef.chan,
 				ifibss->bssid, ifibss->ssid,