wifi: rtl8xxxu: add macids for STA mode

Until now, the driver only assigned a dedicated macid for connections
made in AP mode, in STA mode the return value of rtl8xxxu_get_macid()
was simply 0.
To differentiate between port 0 and 1, when both are in STA mode,
allocate a second macid (with value 1) and set sta_info->macid according
to the used port_num in rtl8xxxu_sta_add().

Signed-off-by: Martin Kaistra <martin.kaistra@linutronix.de>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20231222101442.626837-18-martin.kaistra@linutronix.de