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/rtl818x/rtl8180/dev.c b/drivers/net/wireless/rtl818x/rtl8180/dev.c
index 021d83e..b4218a5 100644
--- a/drivers/net/wireless/rtl818x/rtl8180/dev.c
+++ b/drivers/net/wireless/rtl818x/rtl8180/dev.c
@@ -150,7 +150,7 @@
 			rx_status.freq = dev->conf.channel->center_freq;
 			rx_status.band = dev->conf.channel->band;
 			rx_status.mactime = le64_to_cpu(entry->tsft);
-			rx_status.flag |= RX_FLAG_MACTIME_MPDU;
+			rx_status.flag |= RX_FLAG_MACTIME_START;
 			if (flags & RTL818X_RX_DESC_FLAG_CRC32_ERR)
 				rx_status.flag |= RX_FLAG_FAILED_FCS_CRC;