iwlagn: merge duplicate code into single function

Same operation needed by multiple devices, move to single function.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom.h b/drivers/net/wireless/iwlwifi/iwl-eeprom.h
index c1a17f9..c6f370f 100644
--- a/drivers/net/wireless/iwlwifi/iwl-eeprom.h
+++ b/drivers/net/wireless/iwlwifi/iwl-eeprom.h
@@ -310,5 +310,6 @@
 const struct iwl_channel_info *iwl_get_channel_info(
 		const struct iwl_priv *priv,
 		enum ieee80211_band band, u16 channel);
+void iwl_rf_config(struct iwl_priv *priv);
 
 #endif  /* __iwl_eeprom_h__ */