rtw88: Add update beacon flow for AP mode

To support stations in power saving mode, AP should notify stations
that there are frames buffered at the AP via TIM during beacons.
Driver used to transmit identical beacons that were downloaded to
hardware during the initiation phase. This beacon will become
obsolete over time.

If the beacon does not contain sufficient information, station would
not be able to percept that there is data to receive. Hence it won't
wake up and start the PS-poll procedure, this could lead to timeout
and/or lost data segments. In order to resolve this issue, driver will
now download beacon to hardware whenever the content is updated.

Enable hardware to update dtim_count for more efficiency, this reduces
the overhead of downloading beacon at every beacon interval since most
of the time only the dtim_count needs to be updated.

Change queue mapping for broadcast/multicast frames to high queue, so
these frames can be prioritized and sent when dtim_count is zero.

Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220407095858.46807-4-pkshih@realtek.com