mac80211: limit wmm params to comply with ETSI requirements

ETSI has recently added new requirements that restrict the WMM
parameter values for 5GHz frequencies.  We need to take care of the
following scenarios in order to comply with these new requirements:

1. When using mac80211 default values;
2. When the userspace tries to configure its own values;
3. When associating to an AP which advertises WWM IE.

When associating to an AP, the client uses the values in the
advertised WMM IE.  But the AP may not comply with the new ETSI
requirements, so the client needs to check the current regulatory
rules and use those limits accordingly.

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>