staging: wfx: retrieve greenfield mode from sta->ht_cap and bss_conf

wvif->ht_info contains useless copies of sta->ht_cap and
bss_conf->ht_operation_mode. Prefer to retrieve information from the
original structs instead of rely on wvif->ht_info.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200115135338.14374-13-Jerome.Pouiller@silabs.com


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