mac80211: support RX_FLAG_MACTIME_END

Allow drivers to indicate their mactime is at RX completion and adjust
for this in mac80211. Also rename the existing RX_FLAG_MACTIME_MPDU to
RX_FLAG_MACTIME_START to clarify its intent. Based on similar code by
Johannes Berg.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
[fix docs, atheros drivers]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/drivers/net/wireless/b43legacy/xmit.c b/drivers/net/wireless/b43legacy/xmit.c
index b8ffea6..849a28c 100644
--- a/drivers/net/wireless/b43legacy/xmit.c
+++ b/drivers/net/wireless/b43legacy/xmit.c
@@ -557,7 +557,7 @@
 		status.mactime += mactime;
 		if (low_mactime_now <= mactime)
 			status.mactime -= 0x10000;
-		status.flag |= RX_FLAG_MACTIME_MPDU;
+		status.flag |= RX_FLAG_MACTIME_START;
 	}
 
 	chanid = (chanstat & B43legacy_RX_CHAN_ID) >>