There's a call to object_dynamic_cast() in spapr_vty which uses the type
name "spapr-vty" directly, instead of the usual idiom of using the #defined
TYPE_VIO_SPAPR_VTY_DEVICE.  Fix it.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexander Graf <agraf@suse.de>