wifi: mac80211: don't update rx_stats.last_rate for NDP

wifi: mac80211: don't update rx_stats.last_rate for NDP

If we get an NDP (null data packet), there's reason to
believe the peer is just sending it to probe, and that
would happen at a low rate. Don't track this packet for
purposes of last RX rate reporting.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230608163202.8af46c4ac094.I13d9d5019addeaa4aff3c8a05f56c9f5a86b1ebd@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>