cfg80211: assimilate and export ieee80211_bss_get_ie

This function from mac80211 seems generally useful, and
I will need it in cfg80211 soon.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/cfg80211.h

@@ -604,6 +604,15 @@ struct cfg80211_bss {
 	u8 priv[0] __attribute__((__aligned__(sizeof(void *))));
 };
 
+/**
+ * ieee80211_bss_get_ie - find IE with given ID
+ * @bss: the bss to search
+ * @ie: the IE ID
+ * Returns %NULL if not found.
+ */
+const u8 *ieee80211_bss_get_ie(struct cfg80211_bss *bss, u8 ie);
+
+
 /**
  * struct cfg80211_crypto_settings - Crypto settings
  * @wpa_versions: indicates which, if any, WPA versions are enabled