feat(scheduled mode): wind call chain for FFA_MSG_SEND_DIRECT_REQ

This patch performs the action of winding the SP call chain upon
FFA_MSG_SEND_DIRECT_REQ invocation.

Change-Id: I139a8d0508d97841aaa8f26c8a1e7a0129901b5e
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
diff --git a/src/api.c b/src/api.c
index ceb7934..ab9aa5b 100644
--- a/src/api.c
+++ b/src/api.c
@@ -2599,6 +2599,9 @@
 	assert(next_state == VCPU_STATE_BLOCKED);
 	current->state = VCPU_STATE_BLOCKED;
 
+	plat_ffa_wind_call_chain_ffa_direct_req(vcpus_locked.vcpu2,
+						vcpus_locked.vcpu1);
+
 	/* Switch to receiver vCPU targeted to by direct msg request */
 	*next = receiver_vcpu;