awimage: Add support for WIN32 builds

Signed-off-by: Ithamar R. Adema <ithamar@upgrade-android.com>
awimage: cleanup of TF_DECRYPT_WORKING hack

Signed-off-by: Ithamar R. Adema <ithamar@upgrade-android.com>
awimage: cleanup integer sizes

Signed-off-by: Ithamar R. Adema <ithamar@upgrade-android.com>