refactor(notifications): functions to get notifications

Refactored helper functions for getting notifications from the VM
structure, to prepare for adding framework notifications.

Change-Id: Id90140f99e9bed045b76f842e1e2a1397c0a5847
Signed-off-by: J-Alves <joao.alves@arm.com>
diff --git a/src/api.c b/src/api.c
index e560f8b..2b0a352 100644
--- a/src/api.c
+++ b/src/api.c
@@ -3140,7 +3140,7 @@
 	}
 
 	if ((flags & FFA_NOTIFICATION_FLAG_BITMAP_VM) != 0U) {
-		vm_notifications = vm_notifications_get_pending_and_clear(
+		vm_notifications = vm_notifications_partition_get_pending(
 			receiver_locked, true, vcpu_id);
 	}