PSCI: Add deprecated API for SPD when compatibility is disabled

This patch defines deprecated platform APIs to enable Trusted
Firmware components like Secure Payload and their dispatchers(SPD)
to continue to build and run when platform compatibility is disabled.
This decouples the migration of platform ports to the new platform API
from SPD and enables them to be migrated independently. The deprecated
platform APIs defined in this patch are : platform_get_core_pos(),
platform_get_stack() and platform_set_stack().

The patch also deprecates MPIDR based context management helpers like
cm_get_context_by_mpidr(), cm_set_context_by_mpidr() and cm_init_context().
A mechanism to deprecate APIs and identify callers of these APIs during
build is introduced, which is controlled by the build flag WARN_DEPRECATED.
If WARN_DEPRECATED is defined to 1, the users of the deprecated APIs will be
flagged either as a link error for assembly files or compile time warning
for C files during build.

Change-Id: Ib72c7d5dc956e1a74d2294a939205b200f055613
diff --git a/plat/common/aarch64/plat_common.c b/plat/common/aarch64/plat_common.c
index 90574fd..a6a8476 100644
--- a/plat/common/aarch64/plat_common.c
+++ b/plat/common/aarch64/plat_common.c
@@ -27,7 +27,8 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
-
+#include <assert.h>
+#include <platform.h>
 #include <xlat_tables.h>
 
 /*
@@ -47,3 +48,18 @@
 {
 	enable_mmu_el1(flags);
 }
+
+#if !ENABLE_PLAT_COMPAT
+/*
+ * Helper function for platform_get_pos() when platform compatibility is
+ * disabled. This is to enable SPDs using the older platform API to continue
+ * to work.
+ */
+unsigned int platform_core_pos_helper(unsigned long mpidr)
+{
+	int idx = plat_core_pos_by_mpidr(mpidr);
+	assert(idx >= 0);
+	return idx;
+}
+#endif
+