mac80211: expose HW conf flags through debugfs

This is useful during testing to eg. check the currently
configured HW power save state.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20191119053538.25979-3-thomas@adapt-ip.com


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