iwlwifi: mvm: new BT Coex API

This is the new API for BT Coex. The full functionality
will be implemented in further patches.

Note: this disables BT Coex for the currently existing
fw (-7 version).

There is also a new command - the channel inhibition command.

This command tells BT what channels to avoid in order to
minimise the interaction between BT and WiFi.
We can tell BT about 2 channels, primary and secondary.
BT will not tune to primary at all and will avoid secondary
as much as possible.

This also means that we need to track vifs that AP / GO.
So rename iwl_mvm_bt_coex_vif_assoc to
iwl_mvm_bt_coex_vif_change to better reflect its real
meaning.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>