Add beacon function setting routines for each hardware port.
If beacon function is not enabled, the hardware is not able
to synchronize with AP's beacon and can miss the beacons
under some scenarios such as PS mode.

For AP and Adhoc modes that require to send beacons, do not
update the TSF, otherwise the beacon interval may be affected.
Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>