powerpc: Fix vio build warnings

arch/powerpc/kernel/vio.c:1034: warning: function declaration isn’t a prototype
arch/powerpc/kernel/vio.c:1035: warning: function declaration isn’t a prototype

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/vio.c

@@ -1031,8 +1031,8 @@ void vio_cmo_set_dev_desired(struct vio_dev *viodev, size_t desired) {}
 static int vio_cmo_bus_probe(struct vio_dev *viodev) { return 0; }
 static void vio_cmo_bus_remove(struct vio_dev *viodev) {}
 static void vio_cmo_set_dma_ops(struct vio_dev *viodev) {}
-static void vio_cmo_bus_init() {}
-static void vio_cmo_sysfs_init() { }
+static void vio_cmo_bus_init(void) {}
+static void vio_cmo_sysfs_init(void) { }
 #endif /* CONFIG_PPC_SMLPAR */
 EXPORT_SYMBOL(vio_cmo_entitlement_update);
 EXPORT_SYMBOL(vio_cmo_set_dev_desired);