Rule 8.4: A compatible declaration shall be visible when
          an object or function with external linkage is defined.

Change-Id: I26e042cb251a6f9590afa1340fdac73e42f23979
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

Factor out SPE operations in a separate file.  Use the publish
subscribe framework to drain the SPE buffers before entering secure
world.  Additionally, enable SPE before entering normal world.

A side effect of this change is that the profiling buffers are now
only drained when a transition from normal world to secure world
happens.  Previously they were drained also on return from secure
world, which is unnecessary as SPE is not supported in S-EL1.

Change-Id: I17582c689b4b525770dbb6db098b3a0b5777b70a
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>