feat(indirect messaging): change mailbox state on RX buffer full

Mailbox state transitions from RECEIVED to READ when the VM gets
notification and RX buffer full is set.

Change-Id: Ib90acf4b2949e1164bd7325d6ce14c4d203a37a7
Signed-off-by: Federico Recanati <federico.recanati@arm.com>
diff --git a/inc/hf/vm.h b/inc/hf/vm.h
index 05cd547..356fc7f 100644
--- a/inc/hf/vm.h
+++ b/inc/hf/vm.h
@@ -29,9 +29,9 @@
  *
  * EMPTY is the initial state. The follow state transitions are possible:
  * * EMPTY => RECEIVED: message sent to the VM.
- * * RECEIVED => READ: secondary VM returns from FFA_MSG_WAIT or
- *   FFA_MSG_POLL, or primary VM returns from FFA_RUN with an FFA_MSG_SEND
- *   where the receiver is itself.
+ * * RECEIVED => READ: secondary VM receives an RX buffer full notification
+ *   or primary VM returns from FFA_RUN with an FFA_MSG_SEND where the receiver
+ *   is itself.
  * * READ => EMPTY: VM called FFA_RX_RELEASE.
  */
 enum mailbox_state {