SPM: Deprecate the current implementation

SPM: Deprecate the current implementation

The current SPM is a prototype that only supports one secure partition
in EL0. The objective of SPM is to have multiple partitions. The current
MM interface isn't adequate for this, so it is needed to modify heavily
the code to add proper support for it.

However, there are platforms which are already using this (like SGI) and
removing the code would break it.  For this reason, the current SPM code
has been duplicated in order to temporarily preserve compatibility. All
new improvements/changes to SPM will be done in the non-deprecated copy,
that may change without notice.

The new build option SPM_DEPRECATED has been introduced to select the SPM
implementation. It defaults to 1, that selects the deprecated SPM.

Change-Id: Ic9f80b53b450e97b4d3f47e4ef4a138ee8d87443
Signed-off-by: Antonio Nino Diaz <[email protected]>