iwlwifi: mvm: BT Coex - avoid the shared antenna for management frames

If BT is active, we need to refrain from using the shared
antenna. This logic is done in the firmware when we use the
link quality tables. But for management frames, the rate is
written in the Tx command by the driver.
Hence the driver needs to make sure not use the shared
antenna when BT is active for any frames that don't use
the rate scale table such as management frames or multicast.

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