iwlwifi: mvm: remove color definition

We use the full station field as sta_id, and never
use the color.
FW are about to clean the color out, so those defines
are incorrect now (and were redundant before).

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>