powerpc: Move 32-bit probe() machine to later in the boot process

This converts all the 32-bit platforms to use the expanded device-tree
which is a pretty mechanical change. Unlike 64-bit, the 32-bit kernel
didn't rely on platform initializations to setup the MMU since it
sets it up entirely before probe_machine() so the move has comparatively
less consequences though it's a bigger patch.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/85xx/ppa8548.c

@@ -81,9 +81,7 @@ machine_device_initcall(ppa8548, declare_of_platform_devices);
  */
 static int __init ppa8548_probe(void)
 {
-	unsigned long root = of_get_flat_dt_root();
-
-	return of_flat_dt_is_compatible(root, "ppa8548");
+	return of_machine_is_compatible("ppa8548");
 }
 
 define_machine(ppa8548) {