wifi: rtw89: split out generic part of rtw89_mac_port_tsf_sync()

Originally, rtw89_mac_port_tsf_sync() contains randomization logic
internally. However, not all situation, we need the randomization.
So, split out the generic part from it. And, make the full logic of
original one contained in rtw89_mac_port_tsf_sync_rand(). It will
still be used by its original caller as before. Then, the generic
one will be used in MCC (multi-channel concurrency) management flow.
MCC will implement its logic to decide the offset for TSF sync.

Signed-off-by: Zong-Zhe Yang <kevin_yang@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/20230119062453.58341-3-pkshih@realtek.com