[POWERPC] 4xx: Use machine_device_initcall for bus probe

Some machine_xx_initcall macros were recently added that check for the machine
type before calling the function.  This converts the 4xx platforms to use those
for bus probing.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/platforms/40x/virtex.c

@@ -17,14 +17,11 @@
 
 static int __init virtex_device_probe(void)
 {
-	if (!machine_is(virtex))
-		return 0;
-
 	of_platform_bus_probe(NULL, NULL, NULL);
 
 	return 0;
 }
-device_initcall(virtex_device_probe);
+machine_device_initcall(virtex, virtex_device_probe);
 
 static int __init virtex_probe(void)
 {