mac80211: fix a mistake check for rx_stats update

It should be !is_multicast_ether_addr() in ieee80211_rx_h_sta_process()
for the rx_stats update, below commit remove the !, this patch is to
change it back.

It lead the rx rate "iw wlan0 station dump" become invalid for some
scenario when IEEE80211_HW_USES_RSS is set.

Fixes: 09a740ce

 ("mac80211: receive and process S1G beacons")
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Link: https://lore.kernel.org/r/1607483189-3891-1-git-send-email-wgong@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>