feat(fvp): added calls to unprotect/protect memory

Added SiP calls to FVP platform to protect/unprotect a
memory range.
These leverage rme features to change the PAS of a given
memory range from non-secure to secure.

The mentioned call is leveraged by the SPMC in the memory
sharing flow, when memory is shared from the normal world
onto the secure world.

More details in the SPM related patches.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: Iaf15d8603a549d247ffb1fc14c16bfb94d0e178a
diff --git a/services/std_svc/spmd/spmd_main.c b/services/std_svc/spmd/spmd_main.c
index 5d19868..e200b80 100644
--- a/services/std_svc/spmd/spmd_main.c
+++ b/services/std_svc/spmd/spmd_main.c
@@ -844,7 +844,7 @@
 	unsigned int linear_id = plat_my_core_pos();
 	spmd_spm_core_context_t *ctx = spmd_get_context();
 	bool secure_origin;
-	int32_t ret;
+	int ret;
 	uint32_t input_version;
 
 	/* Determine which security state this SMC originated from */