brcmfmac: correctly report average RSSI in station info

brcmfmac: correctly report average RSSI in station info

The rx_lastpkt_rssi field provided by the firmware is suitable for
NL80211_STA_INFO_{SIGNAL,CHAIN_SIGNAL}, while the rssi field is an
average. Fix up the assignments and set the correct STA_INFO bits. This
lets userspace know that the average RSSI is part of the station info.

Fixes: cae355dc90db ("brcmfmac: Add RSSI information to get_station.")
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210506132010.3964484-2-alsi@bang-olufsen.dk