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>
diff --git a/arch/powerpc/platforms/83xx/mpc837x_rdb.c b/arch/powerpc/platforms/83xx/mpc837x_rdb.c
index 9813c81..667731d 100644
--- a/arch/powerpc/platforms/83xx/mpc837x_rdb.c
+++ b/arch/powerpc/platforms/83xx/mpc837x_rdb.c
@@ -73,7 +73,7 @@
  */
 static int __init mpc837x_rdb_probe(void)
 {
-	return of_flat_dt_match(of_get_flat_dt_root(), board);
+	return of_device_compatible_match(of_root, board);
 }
 
 define_machine(mpc837x_rdb) {