Introduce support for devices that require multiple firmware images.
If a device requires more than a firmware image to operate, load the
image to the appropriate Acceleration Engine (AE).

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>