fix(notifications): encoding of vCPU and receiver IDs

In the FFA_NOTIFICATION_GET interface the vCPU and receiver IDs were
encoded in the wrong positions of w1, according to the FF-A v1.1 beta0
specification.
This patch makes the encoding comply with the spec.

Change-Id: I829ee34145787deeeb2881398667fd338d035332
Signed-off-by: J-Alves <joao.alves@arm.com>
diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index 6b57c92..f90bc41 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -445,7 +445,7 @@
 {
 	return ffa_call((struct ffa_value){
 		.func = FFA_NOTIFICATION_GET_32,
-		.arg1 = (receiver_vm_id << 16) | (vcpu_id),
+		.arg1 = (vcpu_id << 16) | (receiver_vm_id),
 		.arg2 = flags,
 	});
 }