iwlwifi: mvm: BT Coex - fix SYNC2SCO flags

The Sync to SCO is a feature that allows to synchronize
between the WiFi traffic and the expectable BT traffic
when SCO profile is active.
We need to set the validity bit in the command in the init
flow, and set / clear the enablement bit if we want to
enabled / disable the feature.

While at it, clean up the flags that are not used in the
API.

This feature needs to be enabled / disabled easily, so
export its enablement to constants.h.

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