feat(indirect message): forward FFA_RX_RELEASE to SPMC

Within FF-A v1.1 indirect messaging, the SPMC owns a VM's RX buffers;
the Hypervisor must acquire ownership through FFA_RX_ACQUIRE ABI when
it needs to deliver a message to a VM, and notify the SPMC when the VM
releases it, by forwarding FFA_RX_RELEASE messages.

SPMC's view of a VM mailbox may not follow current mailbox
FSM (empty->received->read->empty), SPMC may not be aware of VM
message delivery and the consequent received->read mailbox transition.

Change-Id: I391054410573cc80549905f1a4bd2bbd19ac17fe
Signed-off-by: Federico Recanati <federico.recanati@arm.com>
diff --git a/src/arch/aarch64/hypervisor/handler.c b/src/arch/aarch64/hypervisor/handler.c
index b30fb8d..0ee37d6 100644
--- a/src/arch/aarch64/hypervisor/handler.c
+++ b/src/arch/aarch64/hypervisor/handler.c
@@ -497,7 +497,7 @@
 		*args = api_ffa_features(args->arg1);
 		return true;
 	case FFA_RX_RELEASE_32:
-		*args = api_ffa_rx_release(current, next);
+		*args = api_ffa_rx_release(ffa_receiver(*args), current, next);
 		return true;
 	case FFA_RXTX_MAP_64:
 		*args = api_ffa_rxtx_map(ipa_init(args->arg1),