rtw89: allocate mac_id for each station in AP mode

In station mode, mac_id of station is the same as rtwvif's one.
In AP mode, each station uses individual mac_id.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220107034239.22002-7-pkshih@realtek.com