wl1251: send filters to firmware as they are set

Firmware supports changing filters using ACX_RX_CFG command,
so use it in .configure_filter callback. Firmware also supports
probe request filtering, so add it too along the way.
This will also re-enable BSSID filter which is now removed by
join command while associating.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>