iwlagn: use iwl_eeprom_calib_hdr structure

For retrieve calibration hdr related information, instead of using structure in
one place and #define in other place, unify the method to use data structure.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
index 1301887..e8b324c 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
@@ -96,11 +96,7 @@
 
 u16 iwlagn_eeprom_calib_version(struct iwl_priv *priv)
 {
-	struct iwl_eeprom_calib_hdr {
-		u8 version;
-		u8 pa_type;
-		u16 voltage;
-	} *hdr;
+	struct iwl_eeprom_calib_hdr *hdr;
 
 	hdr = (struct iwl_eeprom_calib_hdr *)iwl_eeprom_query_addr(priv,
 							EEPROM_CALIB_ALL);