[IWLWIFI]: remove per-file CFLAGS for IWL define

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/wireless/iwlwifi/iwl-3945.c b/drivers/net/wireless/iwlwifi/iwl-3945.c
index 55f7d89..acb3875 100644
--- a/drivers/net/wireless/iwlwifi/iwl-3945.c
+++ b/drivers/net/wireless/iwlwifi/iwl-3945.c
@@ -40,6 +40,8 @@
 #include <linux/etherdevice.h>
 #include <linux/delay.h>
 
+#define IWL 3945
+
 #include "iwlwifi.h"
 #include "iwl-helpers.h"
 #include "iwl-3945.h"