staging: wfx: simplify wfx_update_filtering()

wfx_update_filtering() has no reason to instantiate a struct
hif_mib_bcn_filter_enable. Drop it and simplify the code.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200115135338.14374-39-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>