wifi: rtw88: Detect beacon loss with chips other than 8822c

wifi: rtw88: Detect beacon loss with chips other than 8822c

The driver is supposed to avoid entering LPS (power saving) when there
is beacon loss, but only RTL8822C detects the beacon loss (because it
has beacon filtering in the firmware).

Detect beacon loss with the other chips by checking if we received less
than half the expected number of beacons in the last 2-second interval.

This gets rid of the occasional "failed to get tx report from firmware"
warnings with RTL8821AU. It may also avoid some disconnections.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/f52b2fcf-bf94-48bc-89bd-e55ebc3a2f2d@gmail.com