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/src/arch/aarch64/hypervisor/handler.c b/src/arch/aarch64/hypervisor/handler.c
index 9d9250d..c0d8c28 100644
--- a/src/arch/aarch64/hypervisor/handler.c
+++ b/src/arch/aarch64/hypervisor/handler.c
@@ -654,8 +654,8 @@
 		return true;
 	case FFA_NOTIFICATION_GET_32:
 		*args = api_ffa_notification_get(
-			ffa_notifications_get_receiver(*args),
-			ffa_notifications_get_vcpu(*args), args->arg2, current);
+			ffa_receiver(*args), ffa_notifications_get_vcpu(*args),
+			args->arg2, current);
 		return true;
 	case FFA_NOTIFICATION_INFO_GET_64:
 		*args = api_ffa_notification_info_get(current);