cfg80211: fix a crash in nl80211_send_station

mac80211 leaves sinfo->assoc_req_ies uninitialized, causing a random
pointer memory access in nl80211_send_station.
Instead of checking if the pointer is null, use sinfo->filled, like
the rest of the fields.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 779e300..96876d3 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -421,6 +421,7 @@
  * @STATION_INFO_RX_BITRATE: @rxrate fields are filled
  * @STATION_INFO_BSS_PARAM: @bss_param filled
  * @STATION_INFO_CONNECTED_TIME: @connected_time filled
+ * @STATION_INFO_ASSOC_REQ_IES: @assoc_req_ies filled
  */
 enum station_info_flags {
 	STATION_INFO_INACTIVE_TIME	= 1<<0,
@@ -439,7 +440,8 @@
 	STATION_INFO_SIGNAL_AVG		= 1<<13,
 	STATION_INFO_RX_BITRATE		= 1<<14,
 	STATION_INFO_BSS_PARAM          = 1<<15,
-	STATION_INFO_CONNECTED_TIME	= 1<<16
+	STATION_INFO_CONNECTED_TIME	= 1<<16,
+	STATION_INFO_ASSOC_REQ_IES	= 1<<17
 };
 
 /**