cfg80211: handle 6 GHz capability of new station

Handle 6 GHz HE capability while adding new station. It will be used
later in mac80211 station processing.

Signed-off-by: Rajkumar Manoharan <rmanohar@codeaurora.org>
Link: https://lore.kernel.org/r/1589399105-25472-2-git-send-email-rmanohar@codeaurora.org
[handle nl80211_set_station, require WME,
 remove NL80211_HE_6GHZ_CAPABILITY_LEN]
Link: https://lore.kernel.org/r/20200528213443.b6b711fd4312.Ic9b97d57b6c4f2b28d4b2d23d2849d8bc20bd8cc@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>