mac80211: add RX_FLAG_MACTIME_PLCP_START

The timestamp given by iwlwifi is at the beginning of the
frame over the air, at (or during) the SYNC field. Allow
such timestamps to be given to mac80211, at least (for now)
for frames with non-HT/VHT preambles.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 566df20..31337f8 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1010,6 +1010,8 @@
  * @RX_FLAG_MACTIME_END: The timestamp passed in the RX status (@mactime
  *	field) is valid and contains the time the last symbol of the MPDU
  *	(including FCS) was received.
+ * @RX_FLAG_MACTIME_PLCP_START: The timestamp passed in the RX status (@mactime
+ *	field) is valid and contains the time the SYNC preamble was received.
  * @RX_FLAG_SHORTPRE: Short preamble was used for this frame
  * @RX_FLAG_HT: HT MCS was used and rate_idx is MCS index
  * @RX_FLAG_VHT: VHT MCS was used and rate_index is MCS index
@@ -1058,6 +1060,7 @@
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR		= BIT(0),
 	RX_FLAG_DECRYPTED		= BIT(1),
+	RX_FLAG_MACTIME_PLCP_START	= BIT(2),
 	RX_FLAG_MMIC_STRIPPED		= BIT(3),
 	RX_FLAG_IV_STRIPPED		= BIT(4),
 	RX_FLAG_FAILED_FCS_CRC		= BIT(5),