iwlwifi: add set_rxon_chain op

add set_rxon_chain op to iwlwifi cfg ops in preparation of
future 3945 porting work.

Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index 383590c..f5eff74 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -95,6 +95,7 @@
 struct iwl_hcmd_ops {
 	int (*rxon_assoc)(struct iwl_priv *priv);
 	int (*commit_rxon)(struct iwl_priv *priv);
+	void (*set_rxon_chain)(struct iwl_priv *priv);
 };
 
 struct iwl_hcmd_utils_ops {