staging: wfx: drop useless attribute 'filter_mcast'

staging: wfx: drop useless attribute 'filter_mcast'

Currently, wfx_update_filtering() apply the value of wvif->filter_mcast
to the hardware. But an attentive reader will note that
wfx_update_filtering() is always called after set wvif->filter_mcast.
Thus, it not necessary to store filter_mcast in the struct wfx_vif. We
can just pass it as parameter.

Also rename wfx_update_filtering() in wfx_filter_mcast() to reflect this
change.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200415161147.69738-20-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>