awimage: fix compilation error due to TF_DECRYPT_WORKING rework

Signed-off-by: Ithamar R. Adema <ithamar@upgrade-android.com>
README: update status of awimage/awflash projects

Signed-off-by: Ithamar R. Adema <ithamar@upgrade-android.com>
awimage: Add -n flag to disable encryption/decryption (autodetected when unpacking)

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