nl80211: Add wmm rule attribute to NL80211_CMD_GET_WIPHY dump command

This will serve userspace entity to maintain its regulatory limitation.
More specifcally APs can use this data to calculate the WMM IE when
building: beacons, probe responses, assoc responses etc...

Signed-off-by: Haim Dreyfuss <haim.dreyfuss@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>