wifi: rtl8xxxu: extend check for matching bssid to both interfaces

The driver will support two interfaces soon, which both can be in
station mode, so extend the check, whether cfo information should be
parsed, to cover both interfaces.

For better code readability put the lines with priv->vifs[port_num] in a
separate function.

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/20231222101442.626837-8-martin.kaistra@linutronix.de