base-files: Support both model and target in FIT image
BCM pkgtb images have the model/target in the FIT-attribute "target". IOPSYS FIT images have it in the attribute "model". Try model first, then target to support both.
BCM pkgtb images have the model/target in the FIT-attribute "target". IOPSYS FIT images have it in the attribute "model". Try model first, then target to support both.