powerpc: make it compile for multithread change

arch/powerpc/kernel/of_platform.c:479: error: unknown field `multithread_probe' specified in initializer

Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/powerpc/kernel/of_platform.c

@@ -475,9 +475,6 @@ static struct of_platform_driver of_pci_phb_driver = {
        .name = "of-pci",
        .match_table = of_pci_phb_ids,
        .probe = of_pci_phb_probe,
-       .driver = {
-	       .multithread_probe = 1,
-       },
 };
 
 static __init int of_pci_phb_init(void)