wifi: rtw88: Call rtw_fw_beacon_filter_config() with rtwdev->mutex held

rtw_fw_beacon_filter_config() is called once with rtwdev->mutex held
and once without the mutex held. Call it consistently with rtwdev->mutex
held.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221202081224.2779981-3-s.hauer@pengutronix.de