mac80211: Update rate control on channel change

A channel change or a channel bandwidth change can impact the
rate control logic. However, the rate control logic was not updated
before/after such a change, which might result in unexpected
behavior.

Fix this by updating the stations rate control logic when the
corresponding channel context changes.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201206145305.600d967fe3c9.I48305f25cfcc9c032c77c51396e9e9b882748a86@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>