vhost-vdpa: fix typo in a comment

Replace vpda with vdpa.
Signed-off-by: NStefano Garzarella <sgarzare@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220328152022.73245-1-sgarzare@redhat.com>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>

hw/virtio/vhost-vdpa.c

@@ -299,7 +299,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener,
     memory_region_unref(section->mr);
 }
 /*
- * IOTLB API is used by vhost-vpda which requires incremental updating
+ * IOTLB API is used by vhost-vdpa which requires incremental updating
  * of the mapping. So we can not use generic vhost memory listener which
  * depends on the addnop().
  */