fix(cactus): replace tftf_smc with ffa_service_call

For cactus secure partition use ffa_service_call helper routine to make
FFA_SECONDARY_EP_REGISTER_SMC64 call.

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Change-Id: I57aa7709a89cbae983f309ce7ee686ce7117b7d1
diff --git a/spm/cactus/cactus_main.c b/spm/cactus/cactus_main.c
index 50219f3..8ce132c 100644
--- a/spm/cactus/cactus_main.c
+++ b/spm/cactus/cactus_main.c
@@ -217,12 +217,12 @@
 
 static void register_secondary_entrypoint(void)
 {
-	smc_args args;
+	struct ffa_value args;
 
 	args.fid = FFA_SECONDARY_EP_REGISTER_SMC64;
 	args.arg1 = (u_register_t)&secondary_cold_entry;
 
-	tftf_smc(&args);
+	ffa_service_call(&args);
 }
 
 void __dead2 cactus_main(bool primary_cold_boot,