mac80211: fix IBSS join by initializing last_scan_completed

Without this fix, freshly rebooted Linux creates a new IBSS
instead of joining an existing one. Only when jiffies counter
overflows after 5 minutes the IBSS can be successfully joined.
Signed-off-by: Krzysztof Hałasa <khalasa@piap.pl>
[edit commit message slightly]
Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

(cherry picked from commit c7d37a66)
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

net/mac80211/ibss.c

@@ -1091,6 +1091,7 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
 	sdata->u.ibss.privacy = params->privacy;
 	sdata->u.ibss.control_port = params->control_port;
 	sdata->u.ibss.basic_rates = params->basic_rates;
+	sdata->u.ibss.last_scan_completed = jiffies;
 	memcpy(sdata->vif.bss_conf.mcast_rate, params->mcast_rate,
 	       sizeof(params->mcast_rate));