nl80211: Fix regulatory limits for WMM cwmin/cwmax values

nl80211: Fix regulatory limits for WMM cwmin/cwmax values

The internal WMM AC parameters use just the exponent of the CW value,
while nl80211 reports the full CW value. This led to completely bogus
CWmin/CWmax values in the WMM IE when a regulatory limit was present.
Fix this by converting the value to the exponent before passing it on.

Fixes: 636c02c6e9 ("nl80211: Add regulatory wmm_limit to hostapd_channel_data")
Signed-off-by: Felix Fietkau <nbd@nbd.name>