wl1251: fix beacon filter table structure

The beacon filter table configuration ACX structure had certain elements
reversed, fix it to match TI driver.

Based on wl1271 patch 1937e742 by
Juuso Oikarinen.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Acked-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>