iwlwifi: better station table maintenance

This patch makes the station table maintenance safer. Two flags are
maintained:

1) if station is present in driver
2) if station is present in uCode

This will allow us in the future to deal with more stations than the
firmware allows.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-sta.h b/drivers/net/wireless/iwlwifi/iwl-sta.h
index b6bb209..221b93e 100644
--- a/drivers/net/wireless/iwlwifi/iwl-sta.h
+++ b/drivers/net/wireless/iwlwifi/iwl-sta.h
@@ -48,7 +48,7 @@
 int iwl_remove_dynamic_key(struct iwl_priv *priv,
 			   struct ieee80211_key_conf *key, u8 sta_id);
 int iwl_rxon_add_station(struct iwl_priv *priv, const u8 *addr, int is_ap);
-u8 iwl_remove_station(struct iwl_priv *priv, const u8 *addr, int is_ap);
+int iwl_remove_station(struct iwl_priv *priv, const u8 *addr, int is_ap);
 int iwl_get_sta_id(struct iwl_priv *priv, struct ieee80211_hdr *hdr);
 void iwl_sta_modify_enable_tid_tx(struct iwl_priv *priv, int sta_id, int tid);
 int iwl_get_ra_sta_id(struct iwl_priv *priv, struct ieee80211_hdr *hdr);