spm-mm: correcting instructions to build SPM for FVP

Out of two possible implementation of Secure Partition Manager(SPM)
currently only Management mode (MM) design is supported and the support
for SPM based on SPCI Alpha 1 prototype has been removed.

Earlier both implementation used common build flag "ENABLE_SPM" but it
has since been decoupled and MM uses a separate build FLAG "SPM_MM".

Instructions to build it for FVP was still using "ENABLE_SPM", which has
beend corrected in this patch.
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I505b98173d6051816436aa602ced6dbec4efc776

docs/components/secure-partition-manager-design.rst

@@ -119,7 +119,7 @@ Interface). This will be referred to as the *Standalone MM Secure Partition* in
 the rest of this document.
 
 To enable SPM support in TF-A, the source code must be compiled with the build
-flag ``ENABLE_SPM=1``, along with ``EL3_EXCEPTION_HANDLING=1``. On Arm
+flag ``SPM_MM=1``, along with ``EL3_EXCEPTION_HANDLING=1``. On Arm
 platforms the build option ``ARM_BL31_IN_DRAM`` must be set to 1. Also, the
 location of the binary that contains the BL32 image
 (``BL32=path/to/image.bin``) must be specified.
@@ -133,7 +133,7 @@ image in the FIP:
 .. code:: shell
 
     BL32=path/to/standalone/mm/sp BL33=path/to/bl33.bin \
-    make PLAT=fvp ENABLE_SPM=1 ARM_BL31_IN_DRAM=1 fip all
+    make PLAT=fvp SPM_MM=1 EL3_EXCEPTION_HANDLING=1 ARM_BL31_IN_DRAM=1 all fip
 
 Describing Secure Partition resources
 -------------------------------------