iwlwifi: mvm: don't allow diversity if BT Coex / TT forbid it

We should not allow diversity when BT Coex needs the second
antenna. Thermal Throttling can also request to stop using
the second antenna. Honour those requests.

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