rtw88: fix not disabling beacon filter after disconnection

Correct the judgment to let beacon filter disable after disconnection.

Signed-off-by: Chih-Kang Chang <gary.chang@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/20220428020521.8015-2-pkshih@realtek.com