WNM: Workaround for broken AP operating class behavior
Some APs do not advertise operating classes correctly for BSS Transition
Management. Try to determine the most likely operating frequency based
on the channel number (1..14 --> 2.4 GHz; 36..169 --> 5 GHz) if invalid
op_class == 0 is received in a BSS Transition Management Request. This
speeds up the following operating by avoiding a full scan due to an
unknown channel.