fix: make the invocation of ffa_msg_wait v1.1 compliant

The invocation of FFA_MSG_WAIT at secure virtual FF-A instance is
made to be compliant with FF-A v1.1 EAC0 specification. It's
only use is to perform the state transition from RUNNING to WAITING
for the following Partition runtime models: RTM_FFA_RUN,
RTM_SEC_INTERRUPT, and RTM_SP_INIT.

However, the invocation of FFA_MSG_WAIT at non-secure virtual FF-A
instance is made to be compliant with the FF-A v1.0 spec for
legacy reasons.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: Ic63f07c9ce6e6c3be9df2a849900b30eb61fcf6d
diff --git a/src/arch/fake/hypervisor/ffa.c b/src/arch/fake/hypervisor/ffa.c
index 0f45e3b..7515ebb 100644
--- a/src/arch/fake/hypervisor/ffa.c
+++ b/src/arch/fake/hypervisor/ffa.c
@@ -413,14 +413,14 @@
 {
 	return false;
 }
-bool plat_ffa_msg_wait_prepare(struct vcpu *current, struct vcpu **next,
-			       struct ffa_value *ret_args)
+
+struct ffa_value plat_ffa_msg_wait_prepare(struct vcpu *current,
+					   struct vcpu **next)
 {
 	(void)current;
 	(void)next;
-	(void)ret_args;
 
-	return false;
+	return (struct ffa_value){.func = FFA_INTERRUPT_32};
 }
 
 bool plat_ffa_check_runtime_state_transition(struct vcpu *current,