iwlwifi: fix compile warning

Fixes following on big endian systems:
  CC [M]  drivers/net/wireless/iwlwifi/iwl-rx.o
  drivers/net/wireless/iwlwifi/iwl-rx.c: In function ‘iwl_rx_reply_rx’:
  drivers/net/wireless/iwlwifi/iwl-rx.c:1029: warning: integer overflow in
  expression

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reported-by: Marcel Holtmann <marcel@holtmann.org>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c
index 8e1bb53..493626b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-rx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-rx.c
@@ -1044,7 +1044,7 @@
 	 * as a bitmask.
 	 */
 	rx_status.antenna =
-		le16_to_cpu(phy_res->phy_flags & RX_RES_PHY_FLAGS_ANTENNA_MSK)
+		(le16_to_cpu(phy_res->phy_flags) & RX_RES_PHY_FLAGS_ANTENNA_MSK)
 		>> RX_RES_PHY_FLAGS_ANTENNA_POS;
 
 	/* set the preamble flag if appropriate */