rtw88: report RX power for each antenna

Report chains and chain_signal in ieee80211_rx_status.
It is useful for program such as tcpdump to see if the
antennas are well connected/placed.

8822C is able to receive CCK rates with 2 antennas, while
8822B can only use 1 antenna path to receive CCK rates.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Reviewed-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>