iwlagn: merge duplicated code into single place

Multiple places have similar code to construct calib header. Merge into
single inline function.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-ucode.c b/drivers/net/wireless/iwlwifi/iwl-agn-ucode.c
index 4be7a0f..de8277e 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-ucode.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-ucode.c
@@ -183,10 +183,7 @@
 	__le16 *xtal_calib =
 		(__le16 *)iwl_eeprom_query_addr(priv, EEPROM_XTAL);
 
-	cmd.hdr.op_code = IWL_PHY_CALIBRATE_CRYSTAL_FRQ_CMD;
-	cmd.hdr.first_group = 0;
-	cmd.hdr.groups_num = 1;
-	cmd.hdr.data_valid = 1;
+	iwl_set_calib_hdr(&cmd.hdr, IWL_PHY_CALIBRATE_CRYSTAL_FRQ_CMD);
 	cmd.cap_pin1 = le16_to_cpu(xtal_calib[0]);
 	cmd.cap_pin2 = le16_to_cpu(xtal_calib[1]);
 	return iwl_calib_set(&priv->calib_results[IWL_CALIB_XTAL],
@@ -198,14 +195,13 @@
 	struct iwl_calib_temperature_offset_cmd cmd;
 	__le16 *offset_calib =
 		(__le16 *)iwl_eeprom_query_addr(priv, EEPROM_TEMPERATURE);
-	cmd.hdr.op_code = IWL_PHY_CALIBRATE_TEMP_OFFSET_CMD;
-	cmd.hdr.first_group = 0;
-	cmd.hdr.groups_num = 1;
-	cmd.hdr.data_valid = 1;
+
+	memset(&cmd, 0, sizeof(cmd));
+	iwl_set_calib_hdr(&cmd.hdr, IWL_PHY_CALIBRATE_TEMP_OFFSET_CMD);
 	cmd.radio_sensor_offset = le16_to_cpu(offset_calib[1]);
 	if (!(cmd.radio_sensor_offset))
 		cmd.radio_sensor_offset = DEFAULT_RADIO_SENSOR_OFFSET;
-	cmd.reserved = 0;
+
 	IWL_DEBUG_CALIB(priv, "Radio sensor offset: %d\n",
 			cmd.radio_sensor_offset);
 	return iwl_calib_set(&priv->calib_results[IWL_CALIB_TEMP_OFFSET],