iwlwifi: move ucode loading related code to separated file

Multiple iwlagn based devices shared the same ucode loading procedure.
Move loading related code from iwl-5000.c to iwl-agn-ucode.c file.

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 42c291b..a266649 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
@@ -65,6 +65,8 @@
 
 #include "iwl-dev.h"
 
+extern struct iwl_ucode_ops iwlagn_ucode;
+
 int iwl_reset_ict(struct iwl_priv *priv);
 void iwl_disable_ict(struct iwl_priv *priv);
 int iwl_alloc_isr_ict(struct iwl_priv *priv);