SPMD: code/comments cleanup

As a follow-up to bdd2596d4, and related to SPM Dispatcher
EL3 component and SPM Core S-EL2/S-EL1 component: update
with cosmetic and coding rules changes. In addition:
-Add Armv8.4-SecEL2 arch detection helper.
-Add an SPMC context (on current core) get helper.
-Return more meaningful error return codes.
-Remove complexity in few spmd_smc_handler switch-cases.
-Remove unused defines and structures from spmd_private.h

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I99e642450b0dafb19d3218a2f0e2d3107e8ca3fe
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index e4431d2..946a3b8 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -289,7 +289,7 @@
 int plat_spm_sp_get_next_address(void **sp_base, size_t *sp_size,
 				 void **rd_base, size_t *rd_size);
 #if defined(SPD_spmd)
-int plat_spm_core_manifest_load(spmc_manifest_sect_attribute_t *manifest,
+int plat_spm_core_manifest_load(spmc_manifest_attribute_t *manifest,
 				const void *ptr,
 				size_t size);
 #endif