Calculate the position of the control channel in the wide channel
based on the chandef, this is used to obtain the value of N in
802.11be D1.5 Table 9-53a in the column PHY MU/MRU index.

To avoid the need to calculate every frame the value, do it once
monitor vif is added.
Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230305124407.fe9a5b58e241.I291ee480252d098f62d9ec39040284d3e521d88e@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>