feat: runtime model state transition rules

This patch adds the support for various transitions that are
permitted to be made between each vCPU state for a given
partition runtime model.

Refer to section 7 in FF-A v1.1 EAC0 spec.

Change-Id: I22f7168faef9a24b009626999544d94375e45d9c
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
diff --git a/src/arch/fake/hypervisor/ffa.c b/src/arch/fake/hypervisor/ffa.c
index 252d174..b5ea9ae 100644
--- a/src/arch/fake/hypervisor/ffa.c
+++ b/src/arch/fake/hypervisor/ffa.c
@@ -422,3 +422,21 @@
 
 	return false;
 }
+
+bool plat_ffa_check_runtime_state_transition(struct vcpu *current,
+					     ffa_vm_id_t vm_id,
+					     ffa_vm_id_t receiver_vm_id,
+					     struct vcpu *receiver_vcpu,
+					     uint32_t func,  // NOLINTNEXTLINE
+					     enum vcpu_state *next_state)
+{
+	/* Perform state transition checks only for Secure Partitions. */
+	(void)current;
+	(void)vm_id;
+	(void)receiver_vm_id;
+	(void)receiver_vcpu;
+	(void)func;
+	(void)next_state;
+
+	return true;
+}