iwlwifi: introduce beacon context

Only one context can be beaconing at a time,
but we need to track which one. Introduce a
new variable priv->beacon_ctx to do that.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index 289fef8..d2ee55d 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -523,7 +523,8 @@
 
 int iwl_hwrate_to_plcp_idx(u32 rate_n_flags);
 
-u8 iwl_rate_get_lowest_plcp(struct iwl_priv *priv);
+u8 iwl_rate_get_lowest_plcp(struct iwl_priv *priv,
+			    struct iwl_rxon_context *ctx);
 
 u8 iwl_toggle_tx_ant(struct iwl_priv *priv, u8 ant_idx, u8 valid);