iwlwifi: code cleanup for "load ucode" function

Loading uCode functions are shared across multiple agn devices.
Move those functions to iwl-agn-ucode.c file with other uCode
related functions.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.h b/drivers/net/wireless/iwlwifi/iwl-agn.h
index a266649..5af528d 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
@@ -75,4 +75,7 @@
 bool iwl_good_ack_health(struct iwl_priv *priv,
 			 struct iwl_rx_packet *pkt);
 
+/* uCode */
+int iwlagn_load_ucode(struct iwl_priv *priv);
+
 #endif /* __iwl_agn_h__ */