The SPM implementation based on MM is going to be kept for the
foreseeable future.

Change-Id: I11e96778a4f52a1aa803e7e048d9a7cb24a53954
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Acked-by: Sumit Garg <sumit.garg@linaro.org>