mac80211: Let drivers have access to TKIP key offets for TX and RX MIC

Some drivers may want to to use the TKIP key offsets for TX and RX
MIC so lets move this out. Lets also clear up a bit how this is used
internally in mac80211.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index aa8411e..2be7c63 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -241,7 +241,10 @@
 	NL80211_ATTR_MAX = __NL80211_ATTR_AFTER_LAST - 1
 };
 
-#define NL80211_MAX_SUPP_RATES	32
+#define NL80211_MAX_SUPP_RATES			32
+#define NL80211_TKIP_DATA_OFFSET_ENCR_KEY	0
+#define NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY	16
+#define NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY	24
 
 /**
  * enum nl80211_iftype - (virtual) interface types