wifi: rtl8xxxu: remove assignment of priv->vif in rtl8xxxu_bss_info_changed()

priv->vif gets already set in rtl8xxxu_add_interface, there is no need
to set it also in rtl8xxxu_bss_info_changed().

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/20231222101442.626837-2-martin.kaistra@linutronix.de