nl80211: report age of scan results

Linux keeps scan results up to 15 seconds. This can be a problem for fast
moving clients: they get back stale data. But if the kernel reports the age
of the BSS items, then user-space can simply weed out old entries by itself.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index a8d71ed..50afca3 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1277,6 +1277,7 @@
  * @NL80211_BSS_SIGNAL_UNSPEC: signal strength of the probe response/beacon
  *	in unspecified units, scaled to 0..100 (u8)
  * @NL80211_BSS_STATUS: status, if this BSS is "used"
+ * @NL80211_BSS_SEEN_MS_AGO: age of this BSS entry in ms
  * @__NL80211_BSS_AFTER_LAST: internal
  * @NL80211_BSS_MAX: highest BSS attribute
  */
@@ -1291,6 +1292,7 @@
 	NL80211_BSS_SIGNAL_MBM,
 	NL80211_BSS_SIGNAL_UNSPEC,
 	NL80211_BSS_STATUS,
+	NL80211_BSS_SEEN_MS_AGO,
 
 	/* keep last */
 	__NL80211_BSS_AFTER_LAST,