libertas: don't depend on IEEE80211

Runtime-wise we only need escape_ssid from the deprecated IEEE80211
subsystem. However, it's easy to provide our own copy.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/decl.h

@@ -71,4 +71,9 @@ int lbs_stop_card(struct lbs_private *priv);
 void lbs_host_to_card_done(struct lbs_private *priv);
 
 int lbs_update_channel(struct lbs_private *priv);
+
+#ifndef CONFIG_IEEE80211
+const char *escape_essid(const char *essid, u8 essid_len);
+#endif
+
 #endif